Love the custom air freshener........I have the same one except it's blue. My wife says my truck smells like the lake since I go fishing at least 3 times a week so have to use air fresheners. :D
Have you checked the lines for leaks? What year is the truck and mileage? No noise on left turns? Only does this just after putting in drive and not any other time?
Not understanding your question? Dry road = vibration, wet road = no vibration? 4 wheel high I assume. Possible carrier bearing. Is the truck lifter at all?