Just about all of the aftermarket suppliers now have dropped axles and/or modified springs. Truck Shop & Brothers come to mind. Axles are about $400+ and the springs are about $300+. I'm not aware of any dropped spindles for these trucks.
Also, I seem to remember that you have to relocate the tie rod above the spring when you change to lowered springs or axle. This may change the steering geometry somewhat.
Fred
