12 Bolt Compatibility 1970/1981

[brassnut]

I have a gentleman interested in my 12 bolt rear end from my 1981 K5. He has a 1970 K5 with 12 bolt rear as well. He is concerned with the internals and axle shafts in mine being able to fit in his 12 bolt rear end.

Will all of my internals (ring pinion sleeves bearings carrier axle shafts etc...) fit into his 12 bolt? His has 3.08 gears 6 lug drums and 30 spline just as mine has.

Any help or compatibility between the two rearends would be greatly appreciated.

Thanks
Austin

 

[chulisohombre]

I think it is all the same. He would have to reset up gears though. Why doesn't he just swap your axle into his truck. It will bolt in fine. The only thing he has to move and reweld is the shock mounts.

 

[4X4HIGH]

I think it is all the same. He would have to reset up gears though. Why doesn't he just swap your axle into his truck. It will bolt in fine. The only thing he has to move and reweld is the shock mounts AND the SPRING PERCHES.

There, fixed it for you.

 

[chulisohombre]

Scott weren't they the same width. My 82 axle bolted right in to my 72. Just had to move shock mounts up front to match the older 12 bolt. Same as 3/4 ton axle was it not.at least that's what I've always been told. And from me using that axle I didn't have to move the perches.

 

[4X4HIGH]

Scott weren't they the same width. My 82 axle bolted right in to my 72. Just had to move shock mounts up front to match the older 12 bolt. Same as 3/4 ton axle was it not.at least that's what I've always been told. And from me using that axle I didn't have to move the perches.

The FRONT axle is a bolt in between 69-91 blazers but the REAR axle is 69-72 (40.5" perch spacing, same as a 1 ton) and 73-91 (42.5" perch spacing, same as 3/4 ton).

 

[chulisohombre]

The FRONT axle is a bolt in between 69-91 blazers but the REAR axle is 69-72 (40.5" perch spacing, same as a 1 ton) and 73-91 (42.5" perch le thenspacing, same as 3/4 ton).

Wow ok. The junkyard mislabeled my axle then. Mine must be a one ton instead of the 3/4 they said it was. Thanks for clearing that up. I wasn't doughting you man, just thought since mine fit without squeezing the springs, they were the same. Good to know. I can't believe in ten years on here I've never seen that come up before in discussion.