[rwest]

Just thinking out loud, but what about using magnetic sheets to deaden the sheet metal areas?

You’ll need to figure out if the vibration of the panels is causing your noise or if is just the loudness of the mechanical stuff. If it’s a loudness problem, then insulation and filling in gaps where the sound can find its way into the cab would be the answers

If all else fail, louder stereo is always my go to!