Axle swap?

[C15_Sierra]

Would it be possible to swap axles from a 12-bolt 2WD (5-lug) with 2.76's, into a similar-vintage 12-bolt 4WD (6 lug) housing?

Backstory: I'm in the market for putting a 3.73 posi, trying to do it cost effective (my truck's not gonna be a high performance road burner, but I still want some get up and go). 2WD's are rare around here, so 3.73 posi's are few and far between for 2WD trucks.

There's a guy locally who's selling a "early 80s" Chevy 12-bolt posi with 4.10's, but its from a K10, so its 6-lug. Would I be able to swap the axles from my 12-bolt into the other 12-bolt? The 12 bolt for sale has also been recently rebuilt, whereas mine is condition unknown (didn't make any funny noises during the 10 miles I put on it before I took it off the road for the engine swap)

Advice?

[crazy longhorn]

Originally Posted by C15_Sierra

Would it be possible to swap axles from a 12-bolt 2WD (5-lug) with 2.76's, into a similar-vintage 12-bolt 4WD (6 lug) housing?

Backstory: I'm in the market for putting a 3.73 posi, trying to do it cost effective (my truck's not gonna be a high performance road burner, but I still want some get up and go). 2WD's are rare around here, so 3.73 posi's are few and far between for 2WD trucks.

There's a guy locally who's selling a "early 80s" Chevy 12-bolt posi with 4.10's, but its from a K10, so its 6-lug. Would I be able to swap the axles from my 12-bolt into the other 12-bolt? The 12 bolt for sale has also been recently rebuilt, whereas mine is condition unknown (didn't make any funny noises during the 10 miles I put on it before I took it off the road for the engine swap)

Advice?

On your 80 Gmc, you should be able to swap that The axles should also interchange(just look at the drum widths), & if you find them different, you will need to swap your backing plates also. Best of fun,crazyL

[Pyrotechnic]

I believe the shock mounts are different, to make up for the higher ride height that the 4x4 trucks have. Nothing that cant be fixed with a little grinding and welding though.

[Captainfab]

The 12 bolts from '71-'82 are the same width. So as long as both are within that range, the axles will interchange. Also to my knowledge, the last year for the 12 bolt in a K10 was '79-'80, but they were used in the C10's thru '82. I have not tried it, but I have read that the 12 bolt axles will interchange with the 8.5 10 bolt axles.

[C15_Sierra]

A 10-bolt swap is next in line in terms of preference, I have no problems w/ that. Besides, it widens the scope of my search for used parts and makes it easier to find because of the newer squares and OBS trucks that haven't been claimed by rust.

The guy didn't specify year ("early 80s", or maybe he doesn't know what he has), but I figured it being a 12-bolt truck axle with six lugs, it had to come out of a K10

[Captainfab]

Not necessarily. The '63-'70 12 bolts were 6 lug and were available in the C10's with the trailing arm suspension.