I just bought a project car, 88 GTA and the damn RPO tag is gone
I was wondering if there is a way of telling the ratio without taking off the cover??
And if not is it tagged on the gears??

Thanks

 

take the cover off and you'll be 100% sure what you have. as old as it is the code or tag is pretty much meaningless anyway, someone could of swaped parts around.

 

This is true, you know what Im doing this weekend.........

Thanks

 

If they're GM gears, it might be stamped on the ring gear. Mine was stamped 41:11, divide that and you get 3.7272727272 = 3.73. If not , just count teeth and divide!

 

If you don't want to take the diff cover off...

Non-Posi rear: Jack one wheel well off the ground and mark both the wheel and the driveshaft. Have someone slowly turn the wheel two full revolutions while counting the number of turns of the driveshaft.

Posi rear: Jack the rear of the car off the ground and mark both the wheel and the driveshaft. Have someone turn the wheel one full revolution while counting the number of turns of the driveshaft.

I've done this many times either at the wrecker or on a buddy's car. You'd be surprised how well you can eye up the ratio - especially when the 3rd gen ratios are well published. Just over 3 turns = 3.08, 2 and 3/4 turns = 2.73

 

Thanks... That should get me close enough.


Peace

 

Check your RPO codes if you have them, they will tell what came on the car stock.