I am going up to look at my car Friday to see if I have an 8.2 or 8.5, I very positive last time i checked it was a 8.2. In the vendor section above I did not see a sponsor on here for diff parts. I normally check at Randy's ring and pinion or do you guys have a suggestion for good diff part shopping?
Thanks
Ryan

 

If you are referring to your 1971 Cutlass & if the differential is original to the car you have an 8.5" rear end.


Contact Brian Trick or Monzaz (Jim) for parts.

 

I found my ring gear in the garage and put two 1x2" down each side and its measuring just a 1/32 or 1/16 over 8.25". Would that technically be the 8.5? Can't promise grandpa never swapped it for some reason. If I remember correctly stock ratio was 2.73 in this rear end. Thanks!

 

My pinion gear is in a different city with the car and I only have the ring gear here and it counts 41 teeth if that helps me remember 2.73's...

 

If you are measuring a ring gear diameter you have to measure furthest most tooth edge to furthest most tooth edge across the crown NOT the machined back side for diameter. What size ring gear bolt does the ring have? Left hand thread or right hand thread. The pinion will be the identifier for the ring and pinion set. The pinion spline count will tell us everything
10 bolt 8.5 will have 1.625 shaft diameter with 30 spline yoke spline
68-70 8.25 will have 1.875 shaft with 27 spline and finally the 8.2 gear will be 1.438 shaft with 27 spline.
IF you do not have the pinion theh ring gear is junk and can not be used with out its matching pinion.

Jim
J D

 

Besides the cover being on sideways at the moment it looks to be a 8.5!!!

 

And cover

 

I don't know what the 2.73 tooth count is but I know the 2.56 ratio has 41 ring gear teeth and 16 pinion gear teeth.

 

The rear end picture is a 10 bolt 8.5 Olds cutlas or Buicjk Skylark 1971 1972 era.

2.73 ratio is 15 - 41
2.93 ratio is 14 - 41
3.08 ratio is 13 - 40
3.23 ratio is 13 - 42
3.42 ratio is 12 - 41
3.73 ratio is 11 - 41

 

So just like the last 10 bolt Buick rear end my uncle did, it will will take any 10 bolt 8.5 traction device like a modern Trutrac?