1969 GP SJ rear Axle

[chieftan]

I have recently come into a real clean Castilian Bronze 69 GP SJ that I now have the PHS documets.

We are in the beginning stages of restoration. I still cannot prove to myself what rear axle or gear ratio came in the car from the dealership. I belief it to be a Limited slip diff. There are some #’s on the rear pumpkin cover, pass side, however none of them start with 36 + a # that would lead me to use the codes that came back concerning “AXLES”, GP or other Pontiac. The exterior bolt count is 10. Any suggestion as to how to find out for sure that it is, or is not a Posi Trac unit in the car??

2nd) If we take out a limited slip diff & replace it with a Posi Trac unit what value does it detract from car that will be restored 99% to factory specs ??? Consider that if we do take out a Limited slip for a Posi we will install a 4 link suspension step up ??

Other mods we want to upgrade are Headers, Exhaust, disc brakes.

I am really turned off at the idea of building up a HI-PO 428 BB/400 Turbo with Headers & no way to lay down 2 tracks

Thanks, Chieftian

[Larry]

According to Hollander Interchange the axle codes are "letter codes near the carrier." That may take some crawling awound and wire brushing, but I bet you find them. If and when you do, they will be as follows:

Standard Rear
2D & 4D= 2.93
4E= 3.08
2F & 4F= 3.23
4G= 3.36
4H= 3.55

Locking Rear
5D= 2.93
5E= 3.08
5F= 3.23
7G= 3.36
7H= 3.55
7K= 3.90

Hope that helps with some of your identification needs. I realize it doesn't answer the "what came from the factory" question, but it may get you one step closer. If you got the PHS info, there should be an option listed if a heavy-duty Safe-T-track rear end was purchased at $63.00

Now concerns modifications... do it the way you want it to be. The mods you mentions aren't life threatening to the purest... if you ever sold it anyway! Plus, with the current interest in the restomod cars, people are actually paying equal-to or more for "updated" cars.

Keep us posted on your progress on this great GP!

[chieftan]

Larry,

Thanks for your help & suggestions

Greg