Ive got a 12 bolt out of a 70 chevelle. Will it bolt into my 65 skylark ok?I know it is a little wider. thanks
The rear should be a direct swap. As you mentioned, the rear is a bit longer - so you'll need different backspacing on the new rims.
Chev 12 bolt Buick Hello GStage1, The Chev 12 bolt rear is wider, the spring mounts are different, and the upper control arm mounts are in a different location in relation to the pinion. This will change the pinion angle in relation to the drive shaft. Adjustable arms are needed. I decided not to go this route when I beefed up the rear in my 66 GS. I put a 69 Pontiac center section in the 66 rear. This was a four pinion gear posi center section, it was a easy fit, same size bearings, etc. Rich
I just put a 10 bolt out of a Monte Carlo for a short time. I had to buy one of those funny U-joints from Carquest. They had it on the shelf. It was $25.
I put a 12 bolt chev from a chevlle in my 64 no problems it is 1" wider 1/2" each side I use 15X7 buick rallies off a newer Buicks ( more back spacing ) I run 245/60R15's on my 64 and YES they do rub but I cleanced the wheel wells ( mr hammer) the spring pads are not a problem and i had NO other issues at all I even used the same drive shaft. I have done this swap 10 times now and only had to use a conversion U joint a few times. e mail me if you have questions Ken
As I understand it, the 68-72 Chevy 12 bolt A-body rear is the same width as the 64-67 Buick A-body rear and 1" narrower then the 68-72 Buick A-body rear. The 64-67 Chevy 12 bolt A-body rear is 1" narrower then the 68-72 Chevy 12 bolt A-body rear. I have 71 Chevelle 12 bolt (correct #s too) under my 66 that is the same width as the 65 and 66 Buick GS Skylark rears I have "put away." You will need one new Chevy 65-67 upper control arm to clear the bulge on the 12 bolt or you can modify your Buick arm to fit. I have no hop bars that relocate the attachment point on mine so the bulge is no longer an issue for me, but it was when I first put it under. You will need the Buick to Chevy u-joint. You will want to shorten the driveshaft or have interference issues with the transmission yoke to transmission.
This is not what I experienced at all uzzled: and I have swapped many rear ends in my 48 years I may be wrong ( but probably not ) I have 4 64-66 diff's in my yard right now and they are ALL 1" narrower than all 3 of my 68-72 A body CHEV 12 Bolt rear diffs. I maybe wrong but .... uzzled: I can re look at my cars if you want. My 64 post has a 69 442 Olds 12 bolt diff and it is also 1" wider. dont get me wrong but I do not belive you will have any trouble with the swap at all use the same arms as are in your car I did and have done for years I just boxed my uppers for strength Ken :3gears:
I'm with Cheryl! Both my '67 Chevelle 12 bolt and '64 Olds rears are 1 inch narrower than the stock '66 Buick rear. '68-72 Chevelle rears are 1 inch wider than the '67, so that would be the same as a '66 Buick. Confused yet????? You better measure it first!
Oh yeah?!!! Well I'm with Ken too! LOL My 65 Chevelle 12-bolt is the same width as the 64 Skylark 8.2 was, and narrower than the 71 12-bolt I also have in my "stash." I don't know about the control arm issue as I too have the no-hop bars since I installed the 12-bolt. FWIW, I just installed adjustable uppers as I had a feeling my pinion angle was off (high-spped vibration/drone). I had to set them to their minimum length to get the pinion angle set correctly. I always assumed it was the no-hop bars that messed up the pinion angle, but now.. o No: I think the u-joint issue depends on whether you stick with the buick driveshaft or use a Chevy one to get rid of the rubber insulator. Also probably the year or model of car the 12-bolt came in, assuming the later or higher powered cars migh have gotten the larger Buick-sized u-joint. No issues with stock-length driveshaft. I am using the PAE 67 GS400 motormount pads to locate the engine/trans.
