[Skidmark]

Wondering If anyone here has ever installed new gears with posi unit in there 1972 Lemans?
I spoke with a sales guy about upgrading my rear end with something like 3.08, 3.23 or 3.36 gears.
He told me that the 70's were a bit tricky in that I would need to count the teeth on the pinion gear and measure the diameter of the hole of the cap, differential carrier bearing.

When I told him I had the 8.2 scalloped rear end, he said I still needed to take it apart, mock up the caps , measure diameter etc.

I eventually will do as he said ,but in the mean time would like some input from others that have changed out gears in a 72 lemans that came from the factory with 350 2v AT.

My PHS does not indicate any upgraded rear. I can't see on the PHS what plant my car built in, if there where more than one. PHS is poor quality.

Thanks

[big matt]

The body tag on the drivers side top firewall, on top of the cowl will have some info. That will tell you what plant your car was built in, along with color codes, ect.
As for the rear, pull the rear cover. Count the ring gear teeth, then count the pinion teeth. Divide those numbers and thats the current ratio you have.
Is the car in your profile pic the car in reference? That looks like a gto to me. Or to be politically 1972 correct, a lemans with the gto option added. I see ram air fender air extractors and and endura nose. Hell you may already have 3.08's in the car. I am sure thats a 10 bolt, bop rear. If thats the case you just need a rebuild kit with bearings, seals, and limited slip unit. Summit can get you what you seek.

[Shiny]

It has been many years since I rebuilt the 8.2 in my 70.

I ordered the parts from Tom's Differentials in Idaho and at the time, they were very helpful on the phone and familiar with the Pontiacs.

I suggest you call them... https://tomsdifferentials.com/

I remember they warned me about left-hand threads on the ring gear and they were right on target. I think they sold me a US Gear ring and pinion set that was marked with the factory pinion depth setting. Made it easy to set that up.

Their catalog talks to two different seals/yokes so if there are different versions of the 8.2 I think they will know and be able to help you distinguish.

Good luck

[Skidmark]

Originally Posted by big matt

The body tag on the drivers side top firewall, on top of the cowl will have some info. That will tell you what plant your car was built in, along with color codes, ect.
As for the rear, pull the rear cover. Count the ring gear teeth, then count the pinion teeth. Divide those numbers and thats the current ratio you have.
Is the car in your profile pic the car in reference? That looks like a gto to me. Or to be politically 1972 correct, a lemans with the gto option added. I see ram air fender air extractors and and endura nose. Hell you may already have 3.08's in the car. I am sure thats a 10 bolt, bop rear. If thats the case you just need a rebuild kit with bearings, seals, and limited slip unit. Summit can get you what you seek.

Thanks, it's a lemans sport ordered with the gto frt clip. I will follow your advice and check the fire wall tag. It would be great if it did have the 3.08 gears

[Skidmark]

Originally Posted by Shiny

It has been many years since I rebuilt the 8.2 in my 70.

I ordered the parts from Tom's Differentials in Idaho and at the time, they were very helpful on the phone and familiar with the Pontiacs.

I suggest you call them... https://tomsdifferentials.com/

I remember they warned me about left-hand threads on the ring gear and they were right on target. I think they sold me a US Gear ring and pinion set that was marked with the factory pinion depth setting. Made it easy to set that up.

Their catalog talks to two different seals/yokes so if there are different versions of the 8.2 I think they will know and be able to help you distinguish.

Good luck

Thanks a lot. Just the kind of advice I was looking for. I'll give them a call Monday.

[CatalinaMike]

I just did mine. I used a Yukon 8.2 series 3 carrier and 3.55 ring and pinion.