I have had this vehicle for two months and it has spent 20+ days in the shop. The truck vibrates at all speeds above 40 mph and can be felt in the floor, seat, steering wheel ,pedals, etc. Even though multiple dealerships have confirmed there is an issue GM corporate has stated the vehicle is "operating as designed". Not sure which car companies design their truck to make the occupants nauseous. Anyone looking to purchase this truck should research Sierra/Silverado vibration issues and purchase something else. GM isn't going to make it right or fix your issue so steer clear.
I have owned this truck 40 days its been in the service department at least 30 of those. My wife and I are sick over this $48000 purchase. Together we don't make that in a year. Yet the huge corporation seems to take no responsibility for the problems we are having. I can't resell the truck I would be just as wrong as GMC. The only thing anyone wants to do is take it back to the service department. Totally Lost !
Overall it's a nice truck. It rides well, is comfy, and has almost every bell and whistle. Almost everything seems to be at 90% of my expectations. The transmission is constantly searching, and the entertainment system already seems dated.