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I have a 3 speed transmission case pt# 3845122. The pt# is correct for a 56-62 but the date reads E1256. I thought they only used the last digit of the year, and if so this would be May 125, 56. Has anyone seen this before? I am hoping it means May 12,1956.
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Re: 57 Transmission Case
Fred-----
It's possible that the case was cast at Tonawanda. Or, it's possible that Saginaw used the 2 character year code. Although somewhat rare, some Saginaw castings did use a 2 digit year code. Either way, I feel VERY confident that the case casting date represents May 12, 1956. In the event that the case was cast at Tonawanda, I don't know of any "rule" that says that Corvette 3 speed cases were cast only at Saginaw. Regardless of where cast, I would expect that all were machined and assembled at the Saginaw transmission manufacturing plant.
By the way, the reason that C1 differential cases were all cast at Saginaw was that all Corvette units were machined and assembled at Chevrolet-Detroit Gear and Axle. Saginaw was the casting source for that manufacturing plant. Therefore, all Corvette differential cases were cast at Saginaw. For passenger car applications, many of the differential units were manufactured at Chevrolet-Buffalo. Tonawanda was the casting source for Chevrolet-Buffalo. So, differential units manufactured at Chevrolet-Buffalo are all Tonawanda-cast. Since no Corvette differentials were manufactured at Chevrolet-Buffalo, no Corvettes originally used Tonawanda castings. Folks tend to think of these differentials as "Saginaw units" or "Tonawanda units". However, the REAL difference was in the manufacturing plants. So, they're really "Detroit Gear and Axle units" or "Chevrolet-Buffalo units". Only the "Detroit Gear and Axle units" were used in Corvettes. For convenience, we identify those by the source of the casting (because it's easily discernable).
The same is not true for transmissions, though. Regardless of where the castings were produced, and I expect that most, if not all, were cast at Saginaw, the transmissions were all manufactured at Saginaw (not the same plant as the foundry). So, if any Tonawanda-cast cases were used, they could just as easily have been used for a Corvette as a passenger car.In Appreciation of John Hinckley -
Re: 57 Transmission Case
Thanks Joe, I thought the same thing but just needed verification. Also thanks for the differential 101 class. FredComment
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