[GCncsuHD]

Originally Posted by Dieselwrencher

Why do you think the K20 spring widths are different? All the 73-87 GM ones I have seen are 2 1/2". The biggest difference I can think of in K20 and K30 springs is the K30 would have more leafs in the pack. As for the rear use a front leaf spring hanger from a 2wd chassis. Put this in the rear of your rear spring and do a shackle flip. I'd replace the shackle with a heavier unit though. No blocks and = about 4" of lift with a stock shackle. In the front I'd think the 4 leaf K30 springs will be fine for you. I have a few cummins chevy trucks running around with3 and 4 leaf front springs and they work fine. Sway bars are going to help a ton while towing, and air helpers in the rear will help as well. Especially with a bumper pull trailer.

I think maybe meant by the spring width, was actually the distance between the perches? Other than that the difference just being the number of leafs, and the length of the springs. That is the one difference between the K10, K20, and K30 leafs that will determine fitment, K10s would all have 52" leafs, K20 can have 52" or 56" leafs, and K30 will have 56" leafs, so be sure to get the 56" leaf version.

The shackle flip is a good idea, and if you want a easy prebuilt bolt on kit or if you can't find the front leaf hanger to use, I have been thoroughly happy with my ORD shackle flip on my 01 2500HD. This will keep the ride MUCH better than lift springs, while not having the leverage of blocks to cause axle wrap. Compression shackle setups are also known to be more flexy, which can be good, but will also cause a little more sag when towing, shouldn't be an issue with your helper bag setup. Combining the shackle flip with removing a few leaves from the 1 ton setup along with the helper bags should yield the ride and towing ability you need.

Stronger shackles are a good idea, as the stock shackles are known to be weak, and since they are now a compression shackle rather than a tension, they will be subject to more leverage. An easy to come by alternative here would be 2" drop shackles, which when used with the shackle flip actually lift another 1-2" depending on which hole you use. Some are just stamped steel like the stock shackles, but there are some out there that are made out of heavy plate and nice welded construction, along with nice poly bushings. You can usually pick a set up for around $40-50 whereas places like ORD sell a similar shackle for over $100. An example, my Western Chassis brand drop shackles I had on my 03 were 1/4" plate with poly bushings, I only paid $40 for them brand new.