In the front you can use drop torsion keys to get 1"-3" adjustable. For the rear you can use a flip kit (will probably drop it 5"-6"), 3.5" drop leafs (mine dropped me 4.5"), or modify a 4dr tahoe shackle/hanger kit.
I didn't like the load capacity of the belltech drop leafs so I modified a DJM 4dr tahoe shackle hanger kit. It got me 4" drop and I can use my stock leafs. IMO it rides much better now than with the drop leafs.
I used the upper holes of the drop shackle and the barely cleared the fill hose. They have been on for a couple of months now and have had no issues.
First, I unscrewed the stock bolt holding on the driver's side hook in the back cargo area and replaced it with a M10 x 65mm 1.5 pitch bolt. I then used one of these clamps
http://www.fittingsandadapters.com/galsteelvind1.html
and put it around the vent tube next to the filler hose. I tightened it up with a M10 locknut until it lifted the hose up enough to barely clear the shackle.
I can't remember exactly but i believe two new holes were drilled into the frame and one new hole in the hanger (for each side). Then you had to massage the cabin floor a little to clear the hanger. The hardest part about this swap was getting the rivets out, what a pain.
Pics:
Shackles
Drop Hangers