How can I determine which rear end is installed on my 68 400? It has the turbo hydromatic transmission. I was under the impression that a limited slip differential was standard with these packages. I found two sets of numbers "H307" and 9793019. I think these just may be the casting numbers. Where can if find the identifing numbers?

You can find most of the specs here: http://fteufert1.home.att.net/pontiac/page2.htm
Just look under "rear axles". It's a comprehensive list from early 60's to about 79'.

But you'll have to double check your #'s as it should be a double letter Like "ZP". Sorry I can't say for sure, but I thought it was stamped on the housing where the axle tube comes in... not quite sure on that?

Once you have a letter code you should be set. Do you know if it's posi? Do you have any documentation (build sheet etc...)? You might want to get the PHS History. http://www.phs-online.com/
If you didn't know, for $35 you can get them to send you a history packet on your car.

Let us know what you find? Good luck!

Brett - 67 Drop Top 455!

Brett is correct in that it should be a 2 alpha code. As far as location, it is stamped on the axle housing on the drivers side. It is on the rear side of the axle housing mid way between the brake backing and the gear cluster. It can be difficult to find. The letters are pretty small and can be covered in years of dirt and grime. A wire wheel can help scrap off crud in order to find it. I've also found some to be "hidden" beneath the brake line.

Good luck in your search.

Mike

Posi-traction was an OPTION on any Firebird and NOT standard on the 400...In fact, most I've seen didn't have the posi..My 68 400 car is all matching # with a 3.08 open rear..

Gary