The V6 trucks or short wheel base trucks might have softer torsion bars??? I don't know if they do. Maybe a leaf or part of a leaf could be removed from the rear springs? Again the SWB trucks may have less leaf spring in the rear.

 

No. Get rid of the LT tires and go with P metrics for a start. Also replace all of your bushings if you haven't already.

If you read through this whole thread you'd see there's no magic kit out there.