I have done the axle on top of springs a couple times. You have to drill a hole on the bottom of the axle for the center bolt of the springs and use some half size nuts on the U-bolts that you will need to invert, also cut the U-bolts even with the top of the nuts. It will hit bottom pretty easily but you could "C" the frame for additional clearance, remembering to reinforce it. You will lower your truck about 5 inches by this method. You also will have to modify the tie rod to clear the springs. It is a low budget way to get a lot of lowering done, and can be accomplished in a few hours of work in your driveway. Use lowering blocks at the rear and you have a ground hugger.
