OK guys, I'm no dumba$$ when it comes to finding out what parts are and what they fit until this one. I get most of my quality Chevelle parts from the local "Pull and Pay" so I'm used to hunting and finding assorted items that I can make work. Anyway, I found a posi unit under a 1976 Pontiac Grand Prix. It was a 8.2 unit according to the diff cover. The first odd thing to hit me was I thought Pontiac rear ends had a axle bearing set up like a Ford, No C clips? Well, this one had the C clips so I figured it had been changed out to a Chevy at one time or another. Next, when I pulled the posi carrier out it had 12 bolts holding the ring gear on, not the 10 I was expecting. The unit looks to be a Eaton but has only the casting numbers 249 on the carrier housing, not the EDB..140 or EDB..178 I expected. Lastly, OK, I concede I know nothing about Pontiac, but I thought all 8.2 Eaton units had cone type posi guts. This has the flat clutch style like a 12 bolt but its to small to be a 12 bolt. HELP! Oh yeah, The ring and pinon ratio is 41 to 17. What the heck is a 2.41 gear set ????? Regards, Mark aka Arlo

Sounds like the 10 bolt -8.75 coprorate rear.
Here's the part's list so you can see what it came in
http://www.jdrace.com/Rear_ID/12bCHEVY.htm
And judging by the Chevy 12 bolt parts list
http://www.jdrace.com/Rear_ID/12bCHEVY.htm
the carriers might be interchangable if you swap the axle gears.
Freddie or Tom could give you more info.

That's an odd rear end that was used in the mid '70s in mid size GM cars. It was used in some station wagons too. There are no performance parts for it and the rear end will only fit '73 to '77 mid size cars. It is an Eaton Posi, but the only parts that will interchange are the clutch discs, springs and plates. These came with 28 and 31 spline axles.

The 8.2 rear ends were not used after '72, so it couldn't have meen the 8.2 10 bot. The 8.2 will not fit in those cars.

Sounds like the 10 bolt -8.75 coprorate rear....Freddie or Tom could give you more info.

I had one of those rears (2.41:1 gearing :mad: )in my 1977 Oldsmobile 98 Regency with a 403 under the hood. If I'm not mistaken (and I might be) the rears from the 1973-77 A-body cars also fit the 1977-on B & C-body (full-size) cars.

Freddie and Mike, thanks guys. You have solved the oddball dilemma. It sure had me confused. Looked like a 10 bolt, had 12 bolt ring gear. Came from what seemed to be a 8.2 but had super large 31 spline axles and Eaton guts. I have a blast searching the junk yards for parts but even better is when I get an education about those parts. Thanks again for your time and effort. Regards, Arlo

If you can get this thing cheap enoug you might want to save it. They are petty rare now. I see a lot of the posi units at swap meets, but I never see a complete rear end. Many people at swap meets try to rip off people who don't know better by selling these units as 12 bolt Chevy car uints. When someone gets home with one of these and tries to install it in their 12 bolt the find out that they got screwed.