1959 Corvette rear axel

[Timothy A.]

I am new to the Corvette world and I purchased a non-matching numbers 1959 that was basically a basket case. Nothing serious, but wrong parts here and there. I would imagine it was from a 1970's or 80's lame attempt to restore or get back on the road. Here is my question:

I have a pinon seal leak at the rear yoke and I need to replace it. When I looked at all of the numbers on the car, I found the rear end had the following numbers which I do not think is from the car:
Left side - 3726888 GM T

A1864 7

Right side - BW0115

Can anyone help me in identifying the rear end?
Thank you, Tim Allen

[Joe L.]

Re: 1959 Corvette rear axel

Tim-----

I think you'll find that the casting number is "3725899". Casting numbers are notoriously difficult to discern. Any, this would indicate a non-posi axle used between 1957 and 1964 (63-64 for passenger cars only). Any of these differential (i.e "pumpkin") units can be used in a C1 Corvette.

The "BW" codes was used for 1957 and then again for 1959-64. In 1957, it was used for passenger cars with 3.55:1 non-posi axles. For 1959-64 it was used for passenger cars with 3.08:1 non-posi axles. Not only is the code wrong for a Corvette, but this unit was cast at Tonawanda and assembled at the Buffalo Gear and Axle plant. No Corvette units were ever cast at Tonawanda and assembled at Buffalo. However, the unit is 100% functional for a C1 Corvette.

I would say that this unit was assembled in Buffalo on January 15. The casting date coding you report doesn't look right to me, but I do think that it indicates a January, 1957-cast case. So, I would guess that what you have is a 1957 passenger car unit. If so and if it still contains its original gears, it's a non-posi 3.55:1.