Sherman Tank Site News Post 17: Summer is here, I have all kinds of content for updates, but less time than I would like.
I am always tweaking the site and doing minor edits, but in the past few weeks, I’ve had time for some more major projects. There have been a few minor projects worth noting as well.
The Editor over at Tank and AFV News sent me some very interesting reports that give a very interesting look into the Army’s search for a suitable tank Motor.
THE NEW REPORTS! (They are new to the site, not new)
Ordnance Development of the Wright-Continental R-975 Radial Engine: This report is very interesting. It shows how long, and just how far the Army and Continental went to try and improve the life of the R-975 tank motor. By the time they were done, it was almost a new motor, but still not a great tank motor. Good enough for sure, but no Ford GAA, or as reliable as even the A-57!
Ordnance Development of the Chrysler a-57 Multibank Tank Engine:This report is just like the one on the R-975, but all about my favorite tank motor, the Mighty A-57! This motor became shockingly reliable for how complicated it was. What made it great was the complication only came in mating the five motors, the banks themselves were solid, wells designed, motors.
These reports will give you a very good look into why the US Army chose the motors they did and the story behind getting each one to work as a tank motor. They are interesting stories in their own right.
The Sherman had two turret types the 75mm turret and the later T23 turret with the M1 series of 76mm guns. The Jumbo had an up-armored version of the T23 turret.
One of the things that really set the Sherman apart from its peers, and gave it very good longevity, was the size of the turret ring. The Shermans were 69 inches, positively huge for when it was designed, the early T-34 had a 56-inch ring, and the later version with 85mm gun had a 63-inch turret ring. Nazi Germans are not very good in this area, PIII having a 60-inch ring, PIV having only 63 inches, and the Panther only having a 65-inch ring. Even the Tiger wasn’t huge, at only 70 inches! So what makes the size of the ring important? It is one of several factors that determine the maximum size gun you can mount on the tank. The other factors are the mechanical reliability of the vehicle and its load capacity, and how good the country building the tank was at making recoil absorption systems for the guns. The combination of automotive reliability, load capacity, turret ring diameter, and turret size allowed the Sherman to be up-gunned for decades. These factors were far more important than armor thickness when it came to the Shermans longevity. That the Sherman received more powerful guns than the Panther had, or could have had, is just one more reason why the Sherman was such a great tank, and better than the Panther.
Now let’s talk about turret drive motors. There were three types used on the 75mm Shermans.
Oilgear: All models of Sherman tank had both powered and manual turret traverse. They did try various brands and types though. The preferred on the early Shermans was the hydraulic mechanism made by Oilgear Company. The Oilgear unit was both more precise because it had veritable sensitivity and more robust since it was able to keep the turret spinning even with minor flaws in the race or ring gear, than the other choices. Oilgear could not keep up with all the factories producing Shermans, so they had to go to other companies.
The Oilgear unit was hydraulic but powered by its own electric motor that spun a hydraulic pump and turbine setup to rotate the turret. The whole assembly was small enough to be mounted to the side of the turret, with a fair amount of room for the gunner.
Logansport: This Turret drive was very similar to the Oilgear unit, just not as precise, nor as good at dealing with imperfections in the turret race or ring. This unit was so similar the electric motor powering the hydraulic pump and turbine used the same reduction gears as the Oilgear unit.
The Logansport unit used the same mounting bracket as the Oilgear unit as well. The sensitivity to problems with the tolerances on the turret ring would make this drive more likely to fail from minor damage that the Oilgear unit would shrug off.
Westinghouse: The Westinghouse unit was just a big electric motor hooked to reduction gears. Since the motor ran at a faster speed, it had to be adapted to the stabilizer system but was still able to fit the same space and use all the mounting brackets of the other systems.
The Westinghouse unit had the same problem with minor flaws in the race or sensitive to tightness in the ring gear.
Now, this would be a quality assurance problem at the factory in most cases. IE, when the tank got to the end of the line, and the QA inspector rotated the turret, and it screeched and slowed down over 10 degrees of rotation, it would be rejected, and sent to the factory’s QA shop to be fixed. Battle damage might have caused some problems as well, but if the tank took enough of a hit to damage the teeth on the ring, or gear, it was probably going to be knocked out, and in really bad shape. That speculation based on how well many turret rings held up after years on firing ranges when the wreck they were in was restored into a beautiful working tank.
On the later T23 turrets, the Oilgear system was used for traverse control and an improved Westinghouse stabilizer was used as well.
The Westinghouse stabilizer: All models of the Sherman but the 105 armed tanks had a stabilizer to control the main guns in elevation while on the move. It used a gyroscope and hydraulic power pulled from the turret drive system to keep the gun steady in the vertical while on the movie. The system is often disregarded as an advantage by detractors, for a few reasons, but none are valid in a technical sense. The stabilizer was a very advanced piece of kit, and something the Germans could not copy, and never installed a similar system on a wartime tank. That it was complicated and the crews lacked training in using it, doesn’t mean it didn’t work and offer advantages to crews who bothered with it.
The original stabilizer was a little complicated to set up properly since many armor units received their tanks and maybe some manuals for them, when they formed, they often did not have a single man in their company who really knew how to make the stabilizer really work. This lead to it being turned off by a lot of early war crews. The wrongheaded belief the equipment was useless followed that. The Army did a test on it and found the stabilizer, when set up, and used by a crew who knew how to use it, it helped a great deal in getting off a fast first shot when the tank came to stop to shoot. If the tank rocked, the gun stayed more or less on target. This was a big advantage to getting that all important first shot/hit in combat.
The Westinghouse stabilizer was improved and simplified in the second generation Shermans, the large hatch 75 and 76 tanks would have gotten it. It was easier to setup and maintain, and the Army worked on getting crews trained on it.
The M3 2 inch Smoke Mortar: The M3, 2-inch smoke mortar was installed in the turret, with the muzzle opening on the forward left of the turret, on both the 75mm and 76mm gun turrets. It was added to the tank at the request of the British and was loaded and fired by the loader. The mortar was loaded from inside, but protruded into the loaders space, and was not well liked. It could only be aimed by rotating the turret, and not all late model 75mm and 76mm turrets got them. Postwar, most were removed and the hole welded over.
The Hatches: The Sherman’s turret started off with a single large split commander’s hatch. This hatch incorporated the m2 .50 HMG mount and rotated. It also had a standard periscope mounted on one side of the split hatches. This hatch went through several changes through its long life. Initially, the split commander hatch just depended on the weight of the armored hatch cover halves to hold them in the 45-degree angle position that sat in when open. They could be knocked loose when the tank was moving over rough terrain, and really hurt the commander. They added a pair of hatch locks at the factory and fixed them in the field with kits. The final version of the split hatch had internal springs in the hinges to hold them open. There was also a version with a defect that passed factory inspection that showed up on some M4A1 76W tanks, where the split loaders hatch, essentially the same hatch that had been the commander’s hatch, was used for the loader, .50 M2 mount and all. This was fixed pretty quick though, and then the hatch was replaced by the oval loaders hatch.
When the second generation Shermans with the T23 turrets went into production, they all got much improved all-around vision cupolas. There must have been a shortage of contractors who could make it, because it was in short enough supply, the second gen large hatch, M4A2 75s, M4 Composite hulls, and M4 (105) tanks were all built with the original split commanders hatch. The all-around vision cupola production was reserved for tanks armed with the M1A1 gun. The cupola offered very good all around vision, with six armored glass viewing blocks, that were all replaceable, and a larger periscope mounted in a rotating center section of the hatch door. Towards the end of the war, the new cupola became more available and was fitted to some of the ultimate production M4A1 75, M4A3 75w tanks, and M4A3 (105) tanks.
The oval Loaders hatch: The version of this hatch on 75mm turrets looked the same but was slightly smaller than the one used on the T23 turrets. The hatch was a spring-loaded oval hatch, either just big enough to get through or, big enough to get through comfortably, in the T23 versions. On the T23 turrets, when the oval hatch was installed, a new fully rotating periscope foreword of the hatch replaced the one that was mounted in the old split hatch.
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Now for a final bit of information on the turrets and the stuff mounted on them. Over time the turrets picked up an external vane sight the commander could use to roughly put the gunner on a target, it looked like a whale fin in front of the commanders hatch on older 75mm Shermans. This was refined into a more useful, and less odd looking site that could be used from inside or out of the turret. The .50 caliber machine gun mount started on the commander’s hatch, eventually moved to the loaders hatch, and then to the middle between the two hatches. There was also a spotlight mount added, and it ended up being on late 75mm turrets, the T23 76mm turrets and even retrofitted to older 75mm Shermans. The mount had an armored plug, the spotlight plugged into, and could be controlled from inside the tank, much like the spotlights you see mounted to the side of police cars. The turrets also started out with no brackets for storing the heavy machine gun, but they started showing up on 75mm turrets and were on almost all T23 turrets. Even where the lifting eyes were moved around on the turrets.
From looking at period pictures, it was very common for the gunner or loader to ride standing in the commander’s hatch, while he was in it as well, the split hatch cupolas were that big. I thought I wouldn’t see the practice on tanks with the all-around vision cupola, but I found a few were the crews did it there too.
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The standard 75mm Turret: The Sherman’s First Turret, It Had Many Minor Changes
The standard 75mm turret started out with a stubby rotor shield that just covered the base of the 75mm gun. These early turrets didn’t have a direct telescopic sight for the gunner either. The gunner had to rely on the M4 periscope to aim the gun. The turret had one large hatch for the whole turret crew to get in and out from and a pistol port on the loader’s side that could be propped open and spent 75mm shells dumped out. The loader and commander had fully rotating periscopes to view the world through, the commander’s periscope was in his hatch, the loaders right above his station, and the middle of the turret roof had an armored ventilator. Many of these turrets had a weak spot in the armor due to an area machined to fit the turret drive. This area was covered with additional armor on once the problem was discovered.
The small rotor shield and lack of telescopic sight were some of the first production line changes, and older tanks were field modified with kits to update them, often only covering half the turret with added armor on the mantlet to protect the new telescopic site. The new factory full-size rotor shield covered the majority of the turret face with much thicker armor. The next big change was a weak spot in the right side of the casting where a thin spot was made while machining the turret for the gun mount was discovered, and armor was welded on the outside of the turret to thicken it back up. Tanks were retrofitted with this armor in the field, and later the casting was changed to include the thicker armor over the area, eliminating the need for the welded on cheek armor.
At some point, while all the above was going on someone decided the pistol port was a weak spot and it had to go. So they started welding them closed at the factory, and then the casting had them removed. Then the men in the field went ape poop, and they put it back in, around the time the ultimate 75mm turret went into production, with the thicker armor cast in, the pistol port back, a new all-around vision cupola for the commander and an oval hatch for the gunner. This would be the final configuration of the 75mm turret. The tolerances used by US tank factories were close enough turrets cast at one factory could be used at another with no modifications. Many older surplus turrets left over from the tank retriever conversion program were used in later production, with all the updates added, and a hatch cut in for the loader. Due to a shortage of all-around vision cupolas, many 75mm turrets with a loaders hatch ended up with the old split style commander’s hatch.
When hull production switched over to the 47-degree frontal armor configuration, and they went with the large driver and loaders hatches on the M4, M4A2 and M4A3 production, the 75mm turrets needed modification. The hinge for the larger drivers and co-drivers hatches stuck up higher than the older small hatch hulls, they could interfere with the turret’s rotation, since they barely cleared the bustle was the radio was mounted in the back of the turret. The first solution was to notch the bustle a little, but they also changed the turret casting, raising the whole bustle area and making the top of the turret flatter.
The turret drive motor was either an electric motor driven hydraulic system or a straight electric motor driven system. The hydraulic system was the preferred, but when that system was in short supply the electric system was substituted. The 75mm turret could rotate 360 degrees in 15 seconds with the power traverse. It had a manual traverse system as well, and elevation was handled through a manual wheel.
For the very best in minute detail on this subject, please check out the Sherman Minutia site. One minor bit of trivia about the original style turret, the D50878, and D78461 castings, the ones produced for the 105 armed tanks were unique, in that they had an extra armored ventilator whole drilled in so another one could be mounted. So the 105mm turrets really are 105mm only. I’m still not sure if there is a 1/35mm Sherman M4 105, or M4A3 105 with the correct turret.
The T23 Turret: Developed For the Failed T23 program, It Found a New Purpose on The Sherman
While the 75mm turret was still in production and being improved, the T23 turret, taken from the failed T23 medium tank project, went onto the Sherman with the M1A1 gun on the big hatch, wet ammo rack hulls. This turret was larger and could fit the 76mm gun with much more comfort than the basic 75mm turret. All T23 turrets had loaders hatches, though early production T23 turrets used the hatch that had been the commanders hatch on older Shermans for the loaders hatch and used the new all-around vision cupola for the commander. This didn’t last long; it was found the narrow area between the two large hatches on the roof was a weak spot. The big loader’s hatch went away and an oval hatch went in. These turrets had the same traverse speed as the 75mm turret and the same ROF.
The T23 turret came in around 4000 pounds heavier than the 75mm turret. The automotive systems of the Sherman tank were strong enough to support the extra weight without any real change in performance or longevity. The drivetrain didn’t receive any changes at all as far as I can tell, and only the Jumbo tanks got a different gear ratio in the differential. All the extra weight in sandbags, concrete and real armor did shorten the life of the automotive components but not by a significant amount.
All T23 turreted 76mm gun tanks, had wet ammunition storage, as did the Jumbo tanks, but not all large hatch hulls did. The M4 (105), M4 composites, and M4A2 large hatch 75mm tanks all had dry ammo racks. The T23 Turret would get the smoke mortar, and an extra periscope hole machined in when the split loaders hatch was replaced with the oval hatch.
Sources: Armored Thunderbolt by Zaloga, Sherman by Hunnicutt, Ballistics and Gunnery by Bird and Livingston, The Sherman Minutia Site, Son of a Sherman by Stansell and Laughlin, M4 Sherman tank at war by Green, Tanks are a Might Fine Thing by Stout, the Lone Sentry, TM9-731B M4A2, TM9-731G M10A1, TM9-745 GMC M36B2, TM9-748 GMC M36B1, TM9-750M3, TM9-752 M4A3, TM9-754 M4A4, TM9-759 M4A3, FM17-12 Tank Gunnery, FM17-15 Combat Practice firing, FM17-67 Crew Drill and Service of the Piece M4 Series
Most of the information in this section will be a summation of the section from the book Son of a Sherman. Other stuff I had to dig around on the internet for. Anyone who has more info on the tank makers, please feel free to contact me. Parts from all these tank makers would interchange. Many used the same subcontractors. I don’t think anyone has tried or if it’s even possible to track down all the sub-contractors who contributed parts to the Sherman at this point. Some of the manufacturers were more successful than others, some only producing a fraction of the total Sherman production, others producing large percentages. By the end of production, all the US and her allies needs for Shermans were being handled by just three of these factories.
American Locomotive (ALCO)
ALCOalso produced M3 and M3A1 Lees and made Shermans up to 1943. They were a fairly successful pre-war locomotive manufacturer founded in 1901 in Schenectady, New York. They also owned Montreal Locomotive Works. ALCO made several versions of the Sherman, and stayed in the tank game until the late 50s, helping with M47 and M48 production. The company went under in 1969.
Baldwin Locomotive Works (BLM)
Baldwin was another early producer, building three versions of the Lee, The M3A2, M3A3, and M3A5. They mostly built small hatch M4s, with just a handful of M4A2(12). They were out of the Sherman game by 1944 and out of business by 72. They were founded in Philly in 1825 and produced 70,000 steam locomotives before it died.
Chrysler Defense Arsenal (CDA)
Chrysler Defense Arsenal is kind of special. It was a purpose-built tank factory, funded by the US Government, and managed and built by Chrysler. Construction on the factory started in September of 1940. Completed M3 Lee tanks were rolling off the line by April of 1941. This was before the factory was even finished being built. It was built to stand up to aerial bombing. They produced M4A4, and M4 tanks as well and M4 105s, M4A3(105)s, and M4A3 76 tank and nearly 18,000 of them. Chrysler was the sole producer of M4A3E8 76 w Shermans, or the tank commonly known and the Easy 8. They produced 2617 units, but post-war many A3 76 tanks were converted over to HVSS suspension. A very big chunk of the overall Sherman production came from this factory and it went on to produce M26 Pershing tanks.
Chrysler built this factory in a suburb of Detroit, Warren Township Michigan. Chrysler used its many other facilities in the Detroit area as sub manufacturers, and many of their sub-contractors got involved too. CDA not only produced the tanks, it had the capacity to pump out huge numbers of spare parts. CDA lived into the 90s before Chrysler defense systems got sold off to General Dynamics. It took part in making the M26, M46, M47, M48, M60, and M1 tanks.
Federal Machine & Welder (FMW)
I couldn’t find much out about FMW, Son of a Sherman says they were founded in Warren Ohio in 1917. They produced less than a thousand M4A2 small hatch tanks. They were slow to produce them, making about 50 a month. They were not contracted to make any more Shermans after their first 540 total, 1942 contract. They did build some M7 GMCs and M32 tank retrievers. They were out of business by the mid-fifties.
Fisher Tank Arsenal (FTA)
Fisher Tanks Arsenal (FTA) has a lot of common with Chrysler Defense Arsenal, except this time Uncle Sam went to Fisher Body, a division of General Motors. Fisher decided to build the tank plant in Grand Blanc, south of Flint Michigan. The factory broke ground in November of 1941 and the first M4A2 Sherman rolled off the line in January of 1942 before the factory was fully built.
The M4A2 was something of this factory specialty, in particular early on, with them producing a large number of the small hatch M4A2 sent off to Russia, and a few of the rarer large hatch 75mm gun tanks, around 986 small hatch tanks, and about 286 large hatch tanks.
They also produced nearly 1600 large hatch, 76mm gun tanks, or the M4A2 (76)w. These tanks went exclusively to Russia as part of Lend Lease. These tanks were ordered over four different contracts and the final ones off the production line were all HVSS tanks. The HVSS suspension may have seen combat with the Russians before the US Army used it. Oddly, this factory also produced M4A3 76w tanks, but never with the HVSS suspension. Fisher produced a significant number M4A3 and Large hatch 75mm tanks at their factory, but nowhere near their M4A2 production.
Ford Motor Company (FMC)
Ford was a surprisingly small player in the Sherman tale. They are very important in that they developed the Ford GAA V8 covered earlier, and a lot of spare parts. But they only produced 1690 small hatch Shermans between June of 42 and Oct 43. They built a few M10s as well. All these tanks and tank destroyers were produced at their Highland Park facility. After 1943, they stopped building tanks, and wouldn’t get back into until the 50s, and even then it was just for a large production run over a short time, of M48s.
Lima Locomotive Works (LLW)
Lima was one of the first producers of the cast hull M4A1. It did not produce any Lee tanks. Its production capacity had been taken by locomotives to the point just before Sherman production started. They produced the first production M4A1, that was shipped to England, named ‘Michael’, and it’s still on display at the Bovington Museum. They produced Shermans from February of 42 to September of 1943, producing M4A1s exclusively, and they built 1655 tanks. The war was a boon for Lima, they’d been in business since 1870, and the contracts from the military for locomotives really helped them out. Postwar, they failed to successfully convert to diesel-electric locomotives and merged with another firm.
Montreal Locomotive Works (MCW)
MLW was owned by American Locomotive. They produced some wacky Canadian tank based off the Lee chassis, called the Ram, and Ram II, these floppy creations were only armed with a 2 pounder in the Rams case, and a 6 pounder, in the Ram IIs case, and they produced almost 2000 of the wacky things, what’s that all aboot? They eventually got around to producing a proper Sherman tank, the M4A1 “Grizzly”, producing only about 188 tanks. A very few had an all metal track system that required a different sprocket. Other than that, there was no difference between a grizzly and an M4A1 manufactured by any other Sherman builder. Don’t believe the Canadian propaganda about it having thicker armor!
Pacific Car & Foundry (PCF)
PCF was founded in 1905 in Bellevue, Washington. After they bought out there only real competitor in the early 20s, they were the only heavy machinery company and foundry in the Pacific Northwest. They were the go-to foundry for steel used in the building of many Seattle landmarks. In 1924 the founder, William Pigott sold a controlling interest in the company to American Car and Foundry Company. In most stories about a company, it would end right there, but in a twist of fate, the Son of William Pigott, Paul Pigott, bought back a controlling share of the company in 1934.
At first, the company seemed to do ok during the great depression, but it was really on the ropes until just before WWII, when the increase in military spending helped them out. Their steel and aluminum were used in the B17, numerous Naval vessels, and tanks. They were also one of the Sherman tank producers that could produce its own gun mounts and produced enough other Sherman factories used them.
The only west coast tank maker, PCF produced 926 M4A1s from May of 1942 to November of 1943. The foundry had the facilities to produce all the big casting, the M4A1 Sherman used, in-house. As soon as production stopped they started production on the M26 tractor, the truck portion of the M26 tank transporter, also known as the Dragon Wagon. They never got back into tank production again, but they did produce one very special tank destroyer. The almost mythical T28 super heavy tank and the army managed to lose one.
The Shermans they produced were used by units training up and down the west coast, and many were sent to the Pacific. Company A, of the 1st Marine tank battalion, received a 24 of PCF’s M4A1 Shermans, the only ones the Marines would use. These PCF Shermans have a few things that make them easier to identify, the easiest to see is the dust cover mount around the hull machine gun, PCF’s is distinct and made from a strip of steel instead of a rod. Many of these Shermans were produced with the T49 steel tracks. These tanks would see combat in the swamps and jungles of Cape Gloucester. A battle I will cover in detail later.
The T28, also known as the T95 105mm gun motor carriage, two of these massive vehicles were made, and PCF made both. They came in at 100 just under 100 tons and were designed to get a very powerful 105mm gun close enough to knock out heavy fortifications, like the type along the Siegfried line. It was also considered for use in the Invasion of Japan had that been necessary, and man, think of the weird porn the Japanese would come up with if we had invaded with a bunch of these bad boys, instead of nuking them. It had a set of double wide HVSS suspension on each side, with four bogie groups, and armor up to a foot thick. It had a four-man crew and used the same 500 horsepower Ford GAA V8 to move it. Yes, 100 tons, 500HP, a real hot rod that thing was. Development ceased after the war, and any kind of testing on the two prototypes stopped by 47. One prototype burned out, and was scrapped; the other just disappeared for several decades and was found in a remote spot on Fort Belvoir in Virginia. It is now stored in an army parking lot, not open to the public, rusting away.
Pacific Car & Foundry still exist today as PACCAR Inc., one of the largest truck makers in the world. They own both Kenworth and Peterbilt. They also produced much of the steel structure on the Twin towers of the World Trade Center. They built the PACCAR tower in Bellevue in in the late 60s and it’s still their HQ today. They are worth 18,8 billion as of 2013.
Pressed Steel Car (PST)
PSC was one of the big boys of Sherman production, and they also produced the final M4s made, a group of 30 M4A1 76 HVSS tanks. PSC was founded in Pittsburg in 1899, but their tank factory was in Joliet, Illinois. They were the second manufacturer to make the tank and across all the versions they made, they produced 8147 Sherman tanks.
They started tank production with the M3 Lee in June of 41 and stopped production on that in August of 1942. They then produced the M4A1 from March of 42 to December of 43, and the standard M4 from October of 42 to August of 43.
They were one of the final three tank makers to stay in the tank making business after 1943, along with CDA and FTA. PSC would produce large hatch M4A1 76 tanks, including HVSS models late in the run, totaling more than 3400 M4A1 tanks. They produced 21, M4A2 76 HVSS tanks, towards the end of 45.
They were out of business by 56, with no tank production after those final 30 M4A1 76 HVSS tanks.
Pullman Standard (PSCC)
Pullman Standard was a pretty famous luxury train passenger car maker and another company that made rolling stock combined into one company. Pullman Palace Car Co was founded in 1867, or thereabouts. I’m sure some train geek will be dying to fill me in on the company’s history but I’m not really going to look deeply into it. It does make for one of the more interesting stories about a Sherman tank producer. Their main tank factory was in Butler, Pennsylvania. And they helped produce some Grant tanks before they started Sherman production.
They produced the M4A2 from April of 42 to September of 43 and produced 2737 tanks. They also produced 689 standard M4 Sherman tanks from May of 43 to September of 43. Soon after these contracts were finished the US Government broke the company up due to some anti-trust complaint.
The thing to remember about all the Sherman makers is each one had a small imprint on the tanks they produced. So, yes, an M4A1 small hatch tank was the same no matter who made it and all parts would interchange with no modification needed, but the tanks from different makers still had small, cosmetic differences. They may have been something like nonstandard hinges on the rear engine doors to the use of built-up antenna mounts instead of cast. Or wide drivers hoods or narrow, to where the lift rings on the hull were and how they were made or even Chrysler’s unique drive sprocket they put on all their post A4 tanks. None of this meant the parts couldn’t be salvaged and used on another Sherman from another factory without much trouble. Some factories may have produced tanks faster than others, but they all produced them within the specification of the contract or they were not accepted.
Sources: Sherman by Hunnicutt, Son of a Sherman by Stansell and Laughlin, Tanks are a Might Fine Thing by Stout, various company websites