Do any 8.5" 10-bolt axles bolt into a '67 A-Body?
 

Guessing they would be pretty close, but also know that a difference in width of even an inch or two can be a mothertrucker.

Seems like it is the way to go for anything short of drop clutching an 8" tire.

Currently hunting for local W. Michigan boneyards that still have a decent serving of '70s-80's GM iron... geez, this move.

1971-1972 Olds and Buick A-body, they might be an inch wider overall depending on the month of your '67.

I put one in my 65 LeMans without issue, I do not know the overall width difference between the 8.5 and 8.2 as it was a couple years ago but no interference issues rims are 17x8 4.5" BS and tires are 245/45/17 which is 25.8" dia pretty close to the stock wheel/tire diameter. I could fit a 255 not so sure about a 275 but with a 5" BS wheel it would open up more tire options.

Measure the ones you have and compare to the available replacement lengths, Dutchman makes them and not expensive:

https://dutchmanaxles.com/products/s.../gm-axles.html


.

Here's the replacement chart for BOP axle dimensions (attached).



.

71-72 8.5 from Olds & Buick A-body will be the same width as the 66-72 Pontiac A-body 8.2. I have a 66 8.2 and a 71 8.5 in the shop and have verified this. Driveshaft length "may" be slightly different

Just to bump this up the chain a little -

Have been watching the classifieds, Marketplace, CL and it seems like all the 'good' ones are a tough ticket (from the '71-2 Olds/Buick.)

So to the questions:

Plenty of '73-7 A-Body (Monte, Elco, etc) rear ends out there, but not sure about width or if mountings changed. Any info on these in '64-7 / 68-72 A-Body?

How far down the timeline do the ring and pinions interchange... lots of '80s light truck throwaways with 3.42s in that good GM steel out there. Same question for the posi units - are there year specific intervals?

The ‘73 and up rear ends won’t swap into ‘64-‘72 cars.

The control arm mounts are in the wrong location and they’re 1” wider than the widest ‘62-‘72 A-body rears.

The '71-72 8.5 A-body out of an Olds or Buick will measure 61 5/16" wheel mtg surface to wheel mtg surface, that's with original drums installed.

Narrower factory GM A-body rears...
The '64-65 PONTIAC 8.2's, '64-65 Buick 8.2's, '64-67 Chevy 8.2's, & '65-67 "Chevelle" 12 bolts are all of a narrower track design (1/2 to 9/16" narrower on each side).

Have built up becoux of '71-72 8.5 A-body rears for '66 & 67 A-body's & quite a few for '64's & 65's. The tightest fit by far was years ago in a '64 Malibu where the owner was intent on running 275 60-r15's on 15x8.5's. Ended up having to swap out his new rear alum wheels for another part number version that had a different offset.
__________________
Buzzards gotta eat... same as worms.