Originally Posted by Dave_Monica
The newer 4 x 4 trucks sit too high IMO unless you're planning to do any off-roading. I'd seriously look at lowering the truck. There's usually a spacer block mounted between the leaf spring and axle housing that could be replaced with a smaller spacer. If you want to lower the truck at all 4 corners, you could replace the rear spacer and the front coils with pieces from a 2WD...your GM dealer should be able to help you out
The front suspensions on the GM 2 & 4 wheel trucks use torsion bars. Not sure if you can crank the bars "down" to lower the front ride height. On the rear suspension of my '04 K2500HD (a GMT800, not a GMT900) there is a spring perch between the axle & leaf pack, but no spacer. I'm pretty sure the perch is welded to the axle. It might be possible to have "shorter" ones fabbed to reduce the space between the axle & spring.
I've been looking @ 2500HDs the last little while, but haven't looked closely @ the rear suspensions. For the 2011MY, the 2500HD chassis will be different than the 2010 & earlier models.
I have heard of Ford SDs being lowered, but not the GMs.