I have been dealing with the vibration issue for several months now.I have a 2018 Silverado 5.3- 6 speed trans 2 wheel drive and I have 22,000 miles Mine is mostly felt in the steering wheel from 50 to 70 mph. The dealer started by changing the torque converter with no success. The next visit they changed my motor mounts and had no luck. The next visit they did the trans fluid flush and the road force balancing of the wheels and this last time in the shop they took the wheels off a brand new truck on the lot and did a lot of pico scope tests and they had my truck for two weeks They also road force balanced my wheels again. The service manager told me when I picked it up that all the pico scope readings were within spec and that there hands were tied from any further repairs This morning I got the number for GM and called them and they are connecting me with a senior service advisor to get my issue fixed By the way my truck vibrates exactly the same as when I first took it to the dealer