So I have a 1991 trans am gta. It has the l98/ 700r4 combo with a 10 bolt posi rear end.

The rpo codes are:
GU5 (3.23 ratio) and
G80 (positraction lsd)

Heres the problem

I need to find a rebuild kit for it but I don't know how to identify it. I have looked on the axle tubes and found no stampings, there is also no tag on the pumpkin bolts.

I am assuming the rear is stock because it does not look like anything has been tampered with under there (only 70k on the clock so no reason to either...)

So does anyone know the stock specs for this car or a rebuild kit that will work for it?

Or you can give me suggestions on how to find out what rear-end it is.

 

its a 7.5/7.625 a rebuild kit for that would work just fine. It would probably just be bearings and a cover gasket.
is that what your looking for? or a rebuild kit for the posi?

 

The pinion bearing/seal is gone so I figured I'd do all the bearings while I was there.

how do I know if it is 7.5 or 7.625? just take the cover off and measure?

EDIT: and I may do 3.73 gears while im in there too

 

7.5 and 7.625 10 bolts are the same. The only difference is the slightly larger ring gear. Everything else including the carrier (posi) is the same between the 2 diffs.

7.625 started around 1986 so your 91 will be a 7-5/8 but to most people, it's still called a 7-1/2" diff.

Your 91 will also have 28 spline axles.

 

Thanks for your help. Thats all i needed to figure out.