yea im having the same clunkness but only at start form a complete stop like at a stop light. Dealer regreased driveshaft plines then it stopped, but after installed a 2.25" front leveling kit the clunk was back. i now have an diablo 87octane tune, afm off, trans point at 15% & still doing it. so at this point im completely convinced chevy dropped the ball with the drivetrain issues