I received a new 2016 yesterday (ordered new not from current dealer stock) to replace my GMC 2015 6.2 4x4 crew cab that vibrated since I bought it in Dec 2015. My 2015 has been at the dealer since Jan 5th trying to resolve the vibration. They tried wheels, tires, replaced ring & pinion, replaced shocks and are trying shims for the engine next. I'm glad that truck is gone. The new 2016 does not vibrate at all for now and the transmission appears much smoother than the 2015.
Thanks to everyone that takes the time to post what's happening with their trucks on this forum. It helped me get through the last 3 months.