i have a kelderman air ride on a 99 F350 DRW. expensive, but worth it. ride is awesome, kit is very well made, there is nothing wimpy about it. everything fit really well, customer service was excellent. they have kits for stock to 12" of lift, and they also have kits for the front as well.
i have a modification in mind for mine, just need to be able to stay home long enough to do it. i'm going to use a dump valve and a ride height valve from a freightliner tractor, when installed it will hold whatever height it's set for,and dump from a dash switch to load or hook a trailer. i asked about it, kelderman is interested, and wants pictures and a diagram, they might add it as an option later.