I have a kelderman rear on my truck. The previous owner installed and I love it. It doesn't increase load carrying capacity at all but is good for varying the height of the rear,and makes the ride silky smooth. I have a 2wd truck so the coil's up front are pretty smooth anyway,and with the air ride in the rear the truck has very little harshness at all. They do not make a front air bag setup for either 2wd or 4wd 1st gens though(I'm pretty sure of that). the cool thing about the kelderman is that it is a receiver hitch as well. Good bonus.
Chris