If you do a body lift, you need to lengthen the steering shaft... right? I think you could install the redesigned shaft yourself as GM might not honor the fix since you did a body lift. (it doesn't matter if it's out of warranty since it is a design flaw) I think the original problem was the steering shaft , but now exacerbated by the body lift.
gm-techlink.com
Sound from Steering when Driving over Bumps – TechLink
