2010 Chevy Silverado Chevy Silverado 2500HD Vibration

I have a 2010 Chevrolet Silverado 2500 HD WT 6.0 V8 Gas, Crew Cab, Short box. It has 3000 miles on it and is having problems. The problem is that at 1600 rpm and 56 mph it has a vibration in the pedal and steering wheel. It seems rpm related at around 1600 rpm at any speed. Also when I put it into 4WD it gets worse. I have had it to the dealer multiple times and they keep saying that they cannot duplicate the problem. They had me drive another Chevy HD to compare and that truck did not make the same vibration. What is the best way to have GM fix my issue? Is there known GM campaigns around any of my symptoms?

Note: I have had them fix both review mirrors and one electrical window switch.

Thanks,
Derek