I have a 1979 Camaro with a 3.08:1 posi rear end out of an 80 z-28.  I am getting ready to purchase a new ring and pinion set, but I am not sure whether I have a 8.2 or 8.5 inch rear end.  Anyone know any good way to tell short of tearing this thing apart.  I'd rather not spend the money to tear it apart, inspect, re-assemble, drive to the shop, then tear apart again to install the gears. If anyone knows any tip or trick to this, I would appreciate it.  

To the best of my knowledge they quit making the 8.2 in 1972 but you can call summit racing and they should be able to tell you but the only true way to tell is to pull the back cover and measure the ring gear.  

Yeah, that is what I thought too. But when I went to the parts house to get a pinion seal to repair the leaking one, there was options for the 8.2 or 8.5.  Guess the cheapes way will be to buy both seals and see which one fits (hopefully there is an obvious difference).  I will give Summit another try also.  Thanks.  

You can't ever trust the computers at a parts store! I worked at Autozone for three years while I was in school, can't tell you how many times I came across stuff in the computer that was blatantly wrong.

The above post is correct, 8.2-inch 10-bolt product ended int he early 70s, after that it was 8.5" 10-bolt untuil the 3rd Gens came otu and Chevy went ot the pathetic 7.62" 10-bolt.