There were 3 different ratio 8.2 Pontiac 10bolt carriers for both single track & Safe-T-Track usage High ratio = 2.56-2.78 Mid ratio = 2.93-3.08-3.23 Low ratio = 3.36-3.55-3.90-4.11-4.33-4.56-4.88 Eaton posi for the 8.2 only in Low Ratio
As far as a direct bolt-in rear end where no mods are neccessary, other than maybe a rear u-joint swap, these will all fit; '67-69 Firebird, '67-69 Camaro, 10 & 12 bolt, '68-74 Nova & "X" body clones, Ventura, Olds Omega & Buick Apollo. Most common gear ratios to find are 2.56 to 3.08, but they were offered in 3.23 to 4.10, depending on year/model. Positraction, Limited slip, Safe-T-Track, are just different corporate names for the same thing.
Some 71's used the 8.5 some the 8.2, you'll have to check. All 72-75 used the 8.5. All 76-79 with factory V-8 used the 8.5, the 6cyl. in 76-79's used a 7.5. All will bolt in.
The second gen rears as stated will work but the perches would have to moved in.
For WIW I have a 8.2 with an Eaton and so does my brother. Both cars run about 12.80 in 1/4.
The 8.5 are a bit stronger and you would have a few more gear selections to choose.
