There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.
Put one mic on the box itself. Seems to me there was a service bulletin for a flexing box or something with the cab or box mounting bolts. I don't remember the symptoms other than a noise, and I don't remember which year(s) that applied to but it was in the '90s.
Thursday, September 12th, 2013 AT 10:50 AM