The dealership said that the excessive vibration was caused by the center bearing and that the drive shift had to be replaced along with the center bearing. The dealership order the parts over a month ago, and when I called to check up on it they stated that there was a "back order" on these parts. I am still waiting on the part at this time. The dealership said that it was "ok" to drive and that it would not damage anything else which I find hard to believe!! The truck only has about 50,000 miles on it!! It has been used for some towing on a camper trailer and small towing trailer but the majority of miles is going to and from work.