Diff drops won't effect the suspension. It just lowers the front pumkin so that the CVs are level again (basically just compensating for the lift you just installed). 2" diff drop is enough and most are happy with it. I can't remember if the ones that Welder Guy did were 2.5 or 3". We lowered it as much as possible before getting into interference with components in the steering.

You won't lose any appreciable ground clearance with the diff drops. The pumkin will still be above the crossmember. If you drop the crossmember too, then you'll lose some but not much & if you hit sumpn on the trail, the best thing to hit it with is the crossmember anyway.

Here's a pic of mine:

http://www.vehicross.info/gallery/sh...33/ppuser/2699