I have a 4x4 2012 4500 C-C with the Aisin transmission. In late 2019 and 85,000 miles a highspeed thumping vibration started. At 71 mph this vibration can be felt and a hum is also heard. I had the drive shaft rebuilt with new universal joints and it was also balanced. The problem was still present. i had the balance checked and it was good. With the drive shaft removed the vibration is not there. (I have been using the truck without the drive shaft pending finding a trusted shop). The truck runs smooth to 85 mph. The transmission shop I had look at it today could not find a problem with the front end or the transfer case. They think the drive shaft is still the problem and should be replaced. This drive shaft has 3 universal joints with the ball unit on one end. Any help would be appreciated.
Robert
Robert