Nick has the 5.5 beam kit, you need a 5.5 arm kit.
I had the 6.0 kit, which is the same principle but for Edge trucks (that utilize the 4x4 type torsion-bar suspensions). My kit really impressed me, I recently moved up to their long travel race kit because I needed more, but for the money their is no beating it; with nicely valved shocks it will surprise you with it's capability. I ran 33's and have my stock 4.10 gears still, and can do fine. I will be regearing but only because the truck is being linked and I'm getting a 9." What gears do you currently have? What size engine?
If you are serious about getting it (new anyway), let me know and I can get you a discounted price.