I too have been dealing with the vibration issue and pulling to the left on my 2020 3500. Got it 4 weeks ago and have put 4400 miles on it, all the while saying that my steering feels loose in addition to the vibration at highway speeds. Going into dealership today for the third time to get two tires replaced as two were off in the road force balance. Also called them in advance to notify them of the service bulletin. Fingers crossed this solves it.