I had a similar vibration/noise with my 2 ton too. It wasn't there all the time just when it was running at certain speeds.
The problem turned out to be the hangar bearing, on the drivshaft, just behind the cab. The rubber packing around the case had worn away and the bearing was loose. Fixing that up eliminated the vibration and noise. It was suggested, on here, that Devcon might have a product. I looked them up and found a product that looks perfect for the job.
Geo.
