Diffential Identification

[Owen G.]

I have a 1965 Corvette Coupe with matching engine and transmission. I have had the car approximately six years. While doing some number research I noted the following code on the differential case: CA 2 3 64. I was surprised to learn that the housing was from 1964. Consulting my spec guide, I have determined that the 1964 designation CA refers to a build date of February 2nd and a 3.36:1 standard (non-posi). By testing, I have determined my car HAS a posi rear end.The build date for the car is June 8, 1965. I have two questions: (1) Is it possible that a 1964 differential would end up in a 1965 car? (2) Is it possible that the factory would have put a posi rear end in this car ever though the case is marked non-posi. I suspect that somewhere along the life of this car someone switched out non-posi for a posi rear end.

[Joe L.]

Re: Diffential Identification

I have a 1965 Corvette Coupe with matching engine and transmission. I have had the car approximately six years. While doing some number research I noted the following code on the differential case: CA 2 3 64. I was surprised to learn that the housing was from 1964. Consulting my spec guide, I have determined that the 1964 designation CA refers to a build date of February 2nd and a 3.36:1 standard (non-posi). By testing, I have determined my car HAS a posi rear end.The build date for the car is June 8, 1965. I have two questions: (1) Is it possible that a 1964 differential would end up in a 1965 car? (2) Is it possible that the factory would have put a posi rear end in this car ever though the case is marked non-posi. I suspect that somewhere along the life of this car someone switched out non-posi for a posi rear end.

Owen------


Highly unlikely that a differential manufactured in early 1964 would have been factory-installed in a 1965 built near the end of 1965 production. Plus, you know that what's inside is not what the code indicates was originally inside. There's no doubt in my mind that this differential unit was a replacement installed at some time after the car left St. Louis. At this point, the code stamped on the case means nothing since not only has positraction apparently been added but it could very well be that the gear ratio has been changed, too. All that may remain of the original 1964 differential is the carrier case.