Rear axle interchange?

[65standard]

Does anyone know if a 1999 suburban rear axle is the same width as my 1985 C/10. I see it has the same 5x5 bolt pattern. I'm looking for a rear axle with 3.73 posi for my LS swap.

[Rangerman]

Ive been wondering also---

Im wanting to swap the 3:08 open end gears in a 79 to 3:73 with posi.

[Speeding Dakota]

Originally Posted by 65standard

Does anyone know if a 1999 suburban rear axle is the same width as my 1985 C/10. I see it has the same 5x5 bolt pattern. I'm looking for a rear axle with 3.73 posi for my LS swap.

Yes the axles are the same. I put a 3.42 posi out of a 90 burb under my 83 C10.

[68c10owner]

Originally Posted by Speeding Dakota

Yes the axles are the same. I put a 3.42 posi out of a 90 burb under my 83 C10.

A 1990 burb is a different body style than a 1999 burb.

I beleive the 1999 burban will be wider than your truck rearend. THe spring pads may also be in a different place which isnt a big deal and the brakes may be different. It will work but there will be some differences to take into account.

[69heavychevy]

It's not bolt on, different widths...
BTW GM production "posi's" don't hold up very well. Best bet is to add aftermarket gears and posi unit.

[KQQL IT]

Originally Posted by 65standard

Does anyone know if a 1999 suburban rear axle is the same width as my 1985 C/10. I see it has the same 5x5 bolt pattern. I'm looking for a rear axle with 3.73 posi for my LS swap.

http://67-72chevytrucks.com/vboard/s...d.php?t=373438

[65standard]

I'm going to the junkyard now to measure the suburban' s rear axle.

[65standard]

The 1999 suburban rear is 65.5" drum to drum.
My 1985 C/10 rear is 65" drum to drum.

[68c10owner]

Originally Posted by 65standard

The 1999 suburban rear is 65.5" drum to drum.
My 1985 C/10 rear is 65" drum to drum.

So its only .25 wider per side but the spring perches and shock mounts are in different locations. And the oem posi isnt very strong.

[Gregski]

good info ya'll

[65standard]

It might be a bolt-in rear. It has dual spring perches on each side. The inner perches might be for the earlier narrow frame?

For my situation, I'm going to cut off the spring perches anyways as I'm doing an axle flip.

[65standard]

My other choice is this 1990 blazer rear. Direct bolt-in, but it is a 6-lug wheel.

I did snag the blazer's cluster I needed for my LS2 swap and the tilt column.

[Tilt]

I swapped a 90 model Suburban rear end in mine when I did the LS swap. 3.42 limited slip (Gov bomb). As long as you don't beat on it too hard, it should hold up for a while. For now, $150 for the burb rear beat the $1600 that Pyle Bros wanted to build mine.

[68c10owner]

Originally Posted by 65standard

My other choice is this 1990 blazer rear. Direct bolt-in, but it is a 6-lug wheel.

I did snag the blazer's cluster I needed for my LS2 swap and the tilt column.

The only difference between your 85 rearend and the blazer would be the 6 lug axles I believe. Should be able to do a direct swap of the 85 axles into the 90 housing. The 8.5 is pretty beefy. I know of a few 10 second turbo GN`s that still run a 8.5. If you need to rebuild anyway may as well upgrade to better axles.

[mrolds88]

In either 90 or 91 they upgraded from the 28 spline axles to the 30's. Worst case get your 4x4 rear get a set of Dorman axles and use your original brake drums.

[65standard]

Well I picked up the 1999 suburban rear axle with 3.73 gears and Eaton gov locker. Got it on trade for my flipped 1985 rear end. Good deal for me. I'll let you know how it works out.

I passed on the 1990 blazer rear as it was a 3.42 open.

[65standard]

Here us the 1999 suburban rear axle after I cut it out.

[65standard]

And after I stripped axle tubes clean. I will weld Mopar spring perches under the tubes for a flip and fabricate shock mounts.

This axle is only 1/2" wider overall, but it has 2 3/4" wide rear brakes. My original rear only has 2" wide rear shoes. A 3.73 locker rear with bigger brakes for my LSx swap.

[Gregski]

Originally Posted by 69heavychevy

It's not bolt on, different widths...

I recall reading the same thing on this forum somewhere too, different widths, think the Burb is wider

[Gregski]

Originally Posted by 65standard

And after I stripped axle tubes clean. I will weld Mopar spring perches under the tubes for a flip and fabricate shock mounts.

This axle is only 1/2" wider overall, but it has 2 3/4" wide rear brakes. My original rear only has 2" wide rear shoes. A 3.73 locker rear with bigger brakes for my LSx swap.

Sounds like a plan, maybe you can find some wheels with a bit more of an offset to compensate for the 1/4 inch wideness on each side, or not, LOL