'59 rear end numbers

[Terry M.]

I recently looked at a '59 to purchase. There were two numbers on the rear end. On the left side was casting #3725899 and on the right side was a designation of BB 0717. I have two questions. It is advertised as a posi-traction. Is it indeed posi? Second question: What does the designation on the right side indicate? Thanks for the help!

[John H.]

Re: '59 rear end numbers

Terry -

The 3725899 carrier casting was used from '57-'62 for open (non-posi) diffs; I don't show any "BB" codes as ever having been used on Corvettes - might be a passenger car "pumpkin" assembly, cast on July 17th. '57-'61 Posi carriers were casting #3743833, and #3789812 for '62.

[Robert Willis]

Re: '59 rear end numbers

There was a BB in 57 Passenger Cars. BB was a single wheel drive 3.36 for a 57 Chev with an Automatic Transmission . Hope this helps.

http://members.kos.net/willisb/