A-body interchanging differentials?

[jrblanke]

Hey yall,

I have a 64 F85 with an open differential axle assembly. I was wondering if all A-body rears interchange with oldsmobiles. I read some information on this site saying the only axles that interchanged are 64/65 oldsmobiles and 64/65 buicks. Now does this mean that the axle shafts are only interchangeable or does the entire rear axle assembly only interchange between those cars?

Will a 70 chevelle 10 bolt fit a 64 olds f85? How about a 66 chevelle 10-bolt?

Im sorry if my terminology is off. I am talking about swapping the entire axle from drum to drum. Not just the differential unit inside the case or the axles that slide into the case.

What I am after is can I put an axle from a chevelle under my car because it would be easier/less expensive?

Thanks,

James

[don71]

My understanding is the 64-67 years should interchange. So, in your example the 66 chevelle rear would be the way to go. Its because the upper control arms/mounts are different than the later years. This of course does not take into effect the total width of the diff or your drive shaft/yolk differences if any, in your example. There may not be a problem with that, but do your homework to make sure.

This site might explain some of the differences. http://www.oldsmobility.com/

The olds FAQ has some info has well. http://oldsjunction.classicoldsmobile.com/oldsfaq/

[Rallye469]

I've been asking the same thing on a few other sites...
What I've heard(and not confirmed) is that Abody
rears fr4om 64-72 WILL bolt up...but the width is different.

The rear in my '70 will bolt right in to my '65,
however the width of the 70 rear will be 2" wider overall.
It should be easily overcome by a rim with deeper backspacing.

I'd love to hear some real world experience though...

[2blu442]

I too have heard that the 1964-72 will interchange with a slight width difference between 64-67 and 68-72 but have never swapped the rear ends myself. I have put an Olds under a Cheby and right now have a Chev*lle 12 bolt under my 1970 442 and they have a different U-joint, the Olds being bigger. But they make a U-joint that has two caps the correct size for the Chev and two for the Olds, I got mine at a local NAPA parts store but I believe you would be able to find them at any of the large chains. I have both a 1966 rear in the garage and several 68-72 units stacked up behind the garage so if you need it I could take some measurements for you. John

[88 coupe]

Originally Posted by Rallye469

........ I'd love to hear some real world experience though...

My experience here, is with Chevs. Should be the same with Olds.

They are identical, except for width.

'64-'67 in a '68-'72 will get a wider "stance" without changing wheels. '68-'72 in a '64-'67 will get a "narrowed" rear, to use a wider wheel/tire combination.

Norm

[joe_padavano]

There are a few differences. The 64-66 cars have different lower spring perches, for example, but you can swap the springs and housings as a unit. The one thing I've always found confusing is that the Type O axle was first offered in mid-year 67 but with the same width as the 68-72 axles. Also, some of the various GM housings use different upper control arm mounting locations on the housing, so you need to swap the housing and upper arms as a set.

[gearheads78]

Another thing is it is possible to have the wide rear in 66 from the factory. My 66 had the wide rear from the factory. I have been told it depended on what plant it was built in. I have a 72 Cutlass 8.5" rear going in my car and its the exact width of the factory 66 8.2" rear.

[monzaz]

1964-1967 base car models all had the shorter width rears (about 59.5dum to drum)
in 1967 the olds and pontiacs in there sportier cars 442 gto etc got the wider track rears. 1" overall wider. so as long as you have the correct back spacing you will be fine example (IF YOUR RIM IS 4" BACK SPACING YOU WILL NEED TO GO TO 4 1/4" OR 4 1/2" TO PUT THE TIRE BACK INTO ITS ORIGINAL TRACKING SPOT.
1964 1965 rear had flat bolt on sping perch lands for mounting

1967 1968 etc used a pop up cone to keep the spring centered on the perch. So yes spring swap will be needed if you are using these rears . small cost to pay for a better swap.

[Run to Rund]

You won't need a spring swap. the 64-7 spring lower mounts on the housing were flat and a cover cup was bolted on. the later housings have a "bump" stamped into the mounting plate to retain the spring. Spring length is the same, and all years 64-72 use a pigtail on the bottom of the spring.

[monzaz]

I am pretty sure the springs are different on the top or the bottom maybe it was the top having a larger diameter pocket?? Not sure. I knoe the 1968-1972 you can flip the spring up side down and you basically can not tell the difference... Jim

But yes the lower is held in with a cup plate and a bolt and a rubber bushing and or gasket shaped like the spring and cup area too. This was done on the old pontiac and olds rears in the late 50's and early 60's drop out rears too. Jim

[Run to Rund]

The rear spring difference is year based. 64-6 upper pocket in the frame is designed for a tangential end meaning full diameter with the end coil. 64-72 all have a pigtail on the bottom end of the coil. 67-72 have a frame pocket for a pigtail also, so springs for those years have both ends pigtailed.