SInce I owned the truck I have had a bad vibrating/resonating sound upon acceleration. The dealer replaced that Catalytic Convertors, checked the undercarriage, nothing. Can't find a thing. It only happens on occasion. Not cold or hot, warm weather, cold weather. Very annoying. It's almost like its deep in the dash, but it sounds like it's from the engine compartment. It's going in today for the Mobil-1 oil change, front differentail leak, and the vib noise. I't embarrasing when I take clients in my truck and ask, "what the hell is that noise?"