Rear spring perch width on HO72&14 bolt

[jku72]

I remember a discussion on swapping a newer 14 bolt axle under a 3/4 or 1 ton single rear wheel truck. Now I cant find it.
Anyone know where the thread is, or, instead, how much is involved in the swap?

[Yukon Jack]

The 1 ton 14 bolt will have the spring perches in the correct postion for the 67-72. The 3/4 ton spring perches will need to be moved. The measurements are 42.5" for 3/4 tons and 40.5" for 1 ton 14 bolts.

If you are swapping in a 14 bolt, which I am doing shortly on my K5, you will also need a conversion U joint and you will have to address the hard brake line placement. Beast388 has done this conversion so he has given me the above information. If he doesn't see this post, PM him for information.

[Vince M]

I put a '78 3/4 ton into my old '72 3/4 ton with very few problems. I had to...

1. Relocate the spring perches. I cut off the old ones and rewelded them in the correct location.

2. Cut off the shock mounts and reweld them in the correct location.

3. I did not have to do anything with the brake lines. Everything fit.

4. I did not have to do anything with the u-joints. Bolted right in.

5. I took the emergency cables off of the 72 and installed them into the '78 rear.

Hope this helps. There are different versions of the 14 bolt available also. Both a full-floating and a semi-floating. There will be differences between them and again between different years.