I have a 2003 1500 QC hemi 4x4, with 40,000 miles and have noticed recently when towing my boat at low speeds up to about 45 miles an hour there's a strong vibration underneath truck. I checked u-joints on driveshaft and they seem fine. Thinking next that it must be the rear end. I've changed the diff. fluid also putting in the additive, but never pulled the cover. I'm sure from what I've read on hear that my clip is broken on my clutch pack, but has anyone had these symptoms from that problem? Or have any other idea? Thanks for the input!! Buy the way it does'nt vibirate at all when driving truck without boat.