I test drove an '03 3500 SRW 4X4 shortbed last week. I noticed a definite vibration that only occured while the throttle was applied, even slightly. It felt like when I'm on snow in 4x4 in my '95 and hit a patch of dry pavement. It felt drive-line/ auto transmission related.
I told the shop Manager and he drove it, with me as a passenger. He noticed it too and said he would look into it.
The rest of the truck was so smooth and quiet the vibration was very noticable and disappointing. No way I would buy that particular truck and hope it was just a rare defect, not a design issue.
FWIW.