12 bolt rear end

[1972cutlass]

Ive heard that a 1968 thru 1972 GM A Bodies 12 bolt will bolt in a gbody with adjustble upper contol arms does any one no if this will work and is a 8.5 rear out of grandnational or 442 is better to put in my 1982 buck regal a 12 and 8.5 bolt are about the same price new and used.

 

[Oldsmoletick]

GN/442 8.5 rear better? No just easier, it's a direct bolt in, may have to shorten drive shaft a tick, but an 8.5 can be built up to be just about as strong or stronger than a stock 12 bolt, fairly reasonably priced. There are companies that make 12 bolt swap control arms for G body cars, the angles are different, so it's not just a matter of having adjustable control arms. Yes you can wedge it in there with the factory arms, but it won't be right, (I've seen people do it) you'll more than likely have some binding issues, along with your axle not being centered in the wheel well (looks dumb). IMO the 12 bolt is a more permanent upgrade, can be built to withstand far more than the 8.5, Don't get me wrong the 8.5's are good too, but it all depends on what your building the car for. Oh yeah, and the 68-72 rears are a bit wider than the stock g-body rears, so you have to account for that too.

 

[dedub]

I concur with Oldmoletick,
Definitely easier. I did this swap in the summer in my 80 Elky. Found one on-line, replaced bearings and seals, fluid, cylinders and pads and she was like new. Nothing like going from a 10 bolt peg leg to a GN 3.42 posi for under a grand. Recommendation, have your lowers boxed. I was fortunate enough to get some scrap 3/16 steel for free and a neighbor cut and migged it in for me.

Oh, ya, almost forgot... I did have to have my drive shaft shortened about 7/16 of an inch. measure twice cut once!!!

Good luck

 

[1972cutlass]

thanks for all the info