1971 K10 axle swap

[71biggreenk10]

I own a 1971 Chevy K10, I just purchased a set of 1 1/4 ton axles out of a military 1986 Chevy pickup. Do you guys know if they will bolt up? how much will I have to modify? are the spring perches the same width? brake lines the same? etc...

[prostreetC-10]

You are asking that question AFTER you bought them? Did you get a smoking deal on them?

[71biggreenk10]

both axles are fully rebuilt, 4.56 gears, Detroit Locker in the rear, painted, fully assembled lockout to lockout, including 1 ton brakes for the Dana 60 front, and drum to drum for the 14 bolt rear.....$1500 shipped to my door.

[Blazer1970]

Since the mil trucks are a K30 the spring pads are correct and both front and rear axles will bolt in. This assumes that you have the spring plates that go with the axles and the correct u-bolts. The front shock mounts are correct. The rear shock mounts will have to be changed. The steering hooks up the same. This is about as close to "bolt in" as it gets for an axle upgrade.

[71biggreenk10]

That's awesome!!! I looked through a few posts on here about axle swaps in these sort of trucks, but I couldn't find anywhere if it said specifically if there was a difference between the 67-72 spring perches and the 73-87 spring perches. I figured I would have to change the rear shock mount, as both mine are on the same side of the axle, and the 73-87 shock mounts are one on one side the other on the other side of the axle. I did get the spring plates with the axles, but I'll have to get the U-bolts. Do you know if the brake line fittings are the same size? As with these axles I am going from a 1/2 ton brake set up to the 1 ton brake set up. Thank you for all your help already.

[prostreetC-10]

yup....that almost seems like the cost of one if fully rebuild.

[skidder111]

My experience with 73-87 axles (Dana44/14 bolt) going into a 72 K5 is that the front will bolt right in but I had to move the rear perches in board a bit and change the shock mounts. But I'm not sure if the Blazer and the pickup have the same spring locations. Just a thought. Good luck.

[Blazer1970]

Originally Posted by skidder111

My experience with 73-87 axles (Dana44/14 bolt) going into a 72 K5 is that the front will bolt right in but I had to move the rear perches in board a bit and change the shock mounts. But I'm not sure if the Blazer and the pickup have the same spring locations. Just a thought. Good luck.

As long as the 14 bolt came out of a 77 - 91 K30 (one ton), the rear spring perches are the correct width for a '67 - '72 half or 3/4 ton. If you use a 14 bolt from a 3/4 ton you have to move the spring perches in a little.

I think the brake fittings changed in '85, so you will likely have to use hoses for a later model truck.

[skidder111]

Makes sense. They were from a 1980 3/4 ton.

[Blazer1970]

Originally Posted by skidder111

Makes sense. They were from a 1980 3/4 ton.

Yup, the rear spring hangers on a one ton are completely different from a half or 3/4 ton and the springs are spaced closer together.