Another vote for bilsteins. I have revalved and rebuilt motorcycle suspension in the past - the valving on these is perfect out of the box - both high and low speed dampening/ compression and rebound...
I bought a set after 500 miles on my '03 2500hd duramax and immediately for my '05 3500 srw duramax.
MX6 ProComp. Adjustable one in the rear......love them.
2003 Silverado 2500HD 6.0 w/4.10 gears & ProComp MX6 shocks.
2006 Maxlite 29BHS w/Equalizer & Prodigy BC & Honda EU3000i
2001 Camaro SS 6 speed 320RWHP/330RWTQ
A bad day camping beats a good day at work everytime!!!!
Rancho 9000 adjustables here. Over 75000 miles on mine installed on my 2003 Dmax. I like the ability to adjust the ride solo. Run them at 5 front, 7 rear when towing a 14000# 5w. I'll swap the OEMs next time before I put 100 miles on the new truck.
I just put Rancho 9000x on my truck. Performancecenter.com had a good deal running on a package and it came with the remote control system to adjust them from inside the cab. I like the idea of being able to adjust them. AND, if you didn't want the in cab adjuster, I'll bet somebody would be willing to take it off your hands (Mine didn't come with it because of my front coil-over configuration) At any rate, the ride is much better than the stock ride ever was. I think any aftermarket shock (Rancho, Blisten, Monroe, etc.) will be a huge improvement.