Has anyone had similar complaints? I have a 07 Sierra 2500 HD Z71 Offroad Pkg. w/ Duramax and the truck vibrates like crazy from about 40mphand up. Dealer says I have no problem. Help!

If the service tech drove the truck, why does he not find a problem? Seems there is something more to this.

Have you changed out the wheels and tires?
Have you otherwise modified the engine?

If so, look there for your problems.

Has anyone had similar complaints? I have a 07 Sierra 2500 HD Z71 Offroad Pkg. w/ Duramax and the truck vibrates like crazy from about 40mphand up. Dealer says I have no problem. Help!
Is this an 07 classic or new body style? Has the truck been modified (lift, bigger tires or wheels)
I would request that the dealer drive the vehicle with the EVA (they have one) to determine the frequency of the vibration and the intensity.