So the torsion bar is key to the lower control arm. It should be keyed in a way that when the suspension is fully unloaded it still had load on the bar. If this is keyed back into the control arm incorrectly, it wont have this preload anymore.
2005 Silverado 2500, Crew Cab Short Bed. 122,000 miles
MODS: AFE intake, LBZ mouth piece, MBRP cat- less exhaust.