The Torque Converter was replaced due to some shudder in V4 switching to V6 under light throttle. I was excited hoping that some of the other random vibes were shudder also, they were not.
Still vibrating.
I took the truck to a Sierra dealership and just sat down with a service analyst....
They have 4 trucks that they are currently working to fix. They are swapping parts out one by one according to GM's direction. Run the PICO, GM analyzes and provides repair options. Wheels, tires, axles, axle housings, transmission, torque converters, driveshafts, front drive shafts ..... all replaced on a customer's vehicle with no solution to the vibrations.
Confirmed some 2014, 2015, 2016, 2017 have this problem.
Confirmed GM has no idea what the problem or a solution is