will a 64 12bolt fit my 67? what would I need to do if anything to do the swap? thanks in advance...
Greg

yes.

their the same width, mounting points etc.

thank you

will a 64 12bolt fit my 67?.......

:noway: A 12 bolt wasn't offered in Chevelle until 1965, NO 64's. I would ID the rear end before buying.

I had a feeling... I guess i will be looking for the numbers tomorrow... any suggestions what I should be looking for when buying a rear with 3.42 posi(with exception of making sure it is the right one and what year)?

Any 64(65)-72 Chevelle rear end will fit, 68-72 are about 1" wider making tire/wheel fitment different. Just a matter of wheel back space.

Get the casting number, casting date code and axle code. You probably don't need all but might as well.

I have always removed the cover to see what I'm getting and can count the teeth. I recently looked at a rear end that was supposed to be posi but turned out the spiders were welded.

I thought the mounting was different... what would I need to do to mount up a 68-72 12bolt in my 67 10bolt?

oops...I forgot about that.

regardless, all 64 to 67 rears are the same width (excluding late production 67's)

12 bolt rears 65 to 67 should measure around 56.5" flange to flange.

better get all the numbers off of it. including the casting numbers.

inside gearing could have been changed. you'll have to pop the cover.

are you saying the rear your looking at is suppose to have 3.42?

the guy "claims it was from a 64(we know thats wrong) and has 3.42 posi unit...

http://c.im.craigslist.org/P7/rI/SdwNOVtomq8ujUQ9C28z91Y23zVT.jpg

64 Rear end will have flat spring perches with a bolt and spring fitting to hold down the bottom end of the spring on the inside of spring to the rear. 1/2 way thru 67 production year GM changed to a perch with a raised ring, so the spring will not migrate around. I can take pics if you need them.

FYI - I run a 68 12 bolt in my 67. It had a 10 bolt originally.

I can't think of anything special except it's a good time to change bushings and box the lower control arms if not done.

I've heard that the 68-72 upper control arm ears are in a little different position so in the future I'm planning adjustable upper control arms to correct pinion angle if necessary. I've ran it with stock 67 control arms for almost 2 years and no problems.

1967 was a transition year for GM and the Chevelle, the rear axle spring mounting perches changed in 67. The 64-66 lower portion of the rear spring has bolt on clamps and flat spring perch vs. a cup on the rear spring perch that the spring fits over. It has been reported elsewhere in this forum that 1967 may have had both types of rear axle housings installed. I’ve been building and restoring Chevelles for the past 30 years and have owned numerous Chevelles over the past 30 plus years. I’ve never encountered the earlier style of spring mounts on an original 67 A-body vehicle. The earlier axle housings can be installed you may need to make some spring clamps to located the spring, have a spring cup made that can be bolted to the axle housing spring perches.

I've been told the pinion angles are different, but I ran a 68-72 rear in a 66 SS vert for street use and had no problems.

I have been under the impression that swapping a 67 10bolt to a 68+ 12bolt was a big deal... i cant tell you guys how many 68+ rears I passed up not wanted to get into it... one more question for you guys though... what about the control arms? I have some chassisworks boxed arms for my 67 10bolt... If I go to 12 pre or post 67, how much of a difference is there... are these arms going to "the pile"?

I have been under the impression that swapping a 67 10bolt to a 68+ 12bolt was a big deal... i cant tell you guys how many 68+ rears I passed up not wanted to get into it... one more question for you guys though... what about the control arms? I have some chassisworks boxed arms for my 67 10bolt... If I go to 12 pre or post 67, how much of a difference is there... are these arms going to "the pile"?

The lowers are the same for all it's the uppers that changed in 68, so use the control arms you have in the car right now.

mr chevelle... what offset are you running... did you narrow the 68 rear and change your upppers?

The rear end pictured is not a 12 bolt chevrolet. It's a BOP.... or atleast looks to be from the cover. (no eybrow)

Am I right?

mr chevelle... what offset are you running... did you narrow the 68 rear and change your upppers?

275/60 on 8" rim w/5" bs for the track and 225/70 on 7" rim w/4.25" bs on all 4 corners on the street.

I want 8" aluminum wheels but most are made in fractional sizes, at least the ones I want. It would be a lot easier to buy wheels if I had the the correct 67 width rear.

My 68 rear end is stock width (not narrowed) and right now all the control arms are the stock 67's I got with car.

The rear end pictured is not a 12 bolt chevrolet. It's a BOP.... or atleast looks to be from the cover. (no eybrow)

Am I right?

BOP?
Pontiac?

BOP?
Pontiac?

Buick-Oldsmobile-Pontiac (BOP)

The Chevy 12 bolt name pertains to the number of bolts that hold the ring gear to the carrier. By chance or design the chevy 12 bolt can be recognized by 12 bolt covers. As far as I know BOP's with 12 bolt covers have less ring gear bolts. I think they have ten but not sure.

well that just saved me a drive tomorrow... as always, you guys are a HUGE help and I couldn't thank you all enough for the info... If anyone runs into a 12bolt for sale, let me know...
Greg

If the price is right. Just because its not an Chevy 12 bolt does not mean its not worth grabbing. Its still a posi and it will still fit.

will it mount up like a Chevy 12? or am I gonna be getting into something I don't have time for? any differences?

All of these are pretty much the same and should bolt right up. Except for the minor issues already mentioned.

Pop the 10 bolt out and bolt in the 12 in.

If it ends up being the later/wider model, late 67 thru 72. You will be limited on the width of tire you can use. I don't think you will be able to get a 275/60to fit inside the quarters.

I have seen this before on 66 and 67's

The below link has a large amount of information that should answer some questions.

http://www.oldsmobility.com/10bolt-tech.htm (http://www.oldsmobility.com/10bolt-tech.htm)


:secret: The Transmission/Driveline forum would be a better place to post rear end questions and also give the Search function a try.