What the diff.

Help! I have a 71 gs stg 1. How can I tell what chunk I have o No:

Can;t seem to get a straight answer one guy said 8.2 one said 8.5 one said G.M. one B.O.P:blast: I GIVE UP CAN ANYBODY LET ME KNOW?

 

If it is original and not Canadian built it is a GM corporate 8.5.

 

Unless you've had the car since new, you won't know if it's original or not.
BOP vs Chevy is easy to see by the shape of the rear cover.
8.5" vs 8.2" is easy to tell by the pig casting viewed from the rear of the car.

Can you post a picture?

 

The attached picture shows an 8.5" BOP rear.

It's BOP because of the "scallops" on the cover. (The cover isn't a complete oval, it has the "scallops" or "cut outs" on each side)

It's an 8.5" because it has the square "ears" that are pointed out in the casting. An 8.2" would be rounder without the square ears hanging down.

Hope that helps. :TU:

 

my 8.5 rear came from a 71 442 it does not have the square lugs on it.its an odd ball.........

 

That's what mine is I think I have found the answer.. Do they sell a clutch kit for the 8.5 rear end????