The rear bearings are failing in my 67 Cutlass and this seems like a good chance to upgrade. I'm looking for a complete rear axle to either drop in or rebuild then swap out. Since Richmond has the higher numerical sets on eternal backorder, I'm looking for an axle with 3:23 ,3:42 or 3:55 gears and a posi carrier. With my 700R4 swap, the engine lugs around town and at low highway speeds. Would prefer something around Austin, Dallas, Houston, but open to something that meets my needs. I'm open to other options s well, depending Let me know what you have and asking price.
Tim

 

I have the 3:23's in mine with a 200r4 and mine lugs just a little at 55 mph. At 65mph I run about 1900 rpm. I would recommend the 3:42's or taller.

 

I have an O-axle with Richmond 4:10's.Will that work.I do a lot of 3:90 & 4:10 rears for the guys with overdrives,and they haven't regretted it,but it all depends on what you are looking for.
I can build anything you want.I have the 71-72 8.5" 10-bolts,and 12-bolt Chevy rears as well.

 

The 66-67 track width is 1" (total) shorter than the 68-72 axle which is a benefit (maybe) as it will put the tires outboard a little for you. Id go with a corporate 8.5" 10 bolt carrier found on the 71 & 72s. The part availability is considerable compared to the "O" type 8.5, as you have found. Why not have 507 build you one? Now you have to decide 391s or 410s. Have to do the math or 507 can comment on what the actual difference would mean RPM wise with an OD.

 

Actually,Chevelles had the narrower rears from 64-67. All of the other A-bodies only had the narrower rear for 64-65.
With that being said,all of the 12-bolt O-axles are the same width.They are the same width as the 71-72 8.5" 10-bolt,and the 68-72 12-bolt Chevy

 

I would have sworn the 66-67 were shorter too? We took one out of a 67 and tried to fit it into a 68 and it measured 1" total shorter. That was the early 80s so it was before I knew anything about Olds. This was a race car 67, 442 so who knows it was most likely replaced with a Chevy or an earlier Olds? The 67 was well beaten upon. Thanks for the correction. Who can argue with 507 he apparently is up to his neck in rear ends!

 

Definitely not my first rodeo.