8.2 or 8.5 rear ??
 

I would like to change the pinion bearings in my 71 GTO and would like to get all the parts ahead of time. Before I order the parts I need to figure out what it is... other than a 3.23, 10 bolt. Apparently it could be either an 8.2 or an 8.5 and have either a 25, 27 or 30 spline pinion. I looked at the original build sheet and my PHS documents but still can't figure out what I have. Is there an easy way to tell, without any diassembly or am I missing something in the documents I have? Also, are there any recommendations on where to get a rebuild kit/bearings?
Thanks in advance guys.

Glen.

From the factory, a 71 GTO would have a 8.2 BOP 10 bolt, 27 spline pinion stem, 28 spline non-cclip axles, 7/16 LH ring gear bolts. Chevelle and Monte Carlo El Camino had 8.2 10 bolt Chevy, c-clip axles, 25 spline pinion stem through 72. 71-72 Buick and Olds had 8.5 10 bolts 30 spline pinion without c-clips, known originally as the B and O axle, later to become the corporate GM 10 bolt 8.5. The rear end cover on a 71-72 Buick or Olds 8.5 10 bolt looks the same with the crecent notches left and right on the rear end cover as the BOP 8.2 does. Although, the 8.5 has large 'squared lugs' sticking out of the left and right of the rear end housing. I believe the Chevy 8.2 will have the oil groove stamped into the cover for lubricating the carrier bearings. The chevy 'c-clip' will neck down on the axle tube right before the backing plate. The backing plates will be held by nuts and bolts. The axle tubes on the 8.2 BOP and 8.5 71 72 B and O will neck up just before the backing plate and oval headed studs will be visible retaining the backing plates.