Stop in for a cup of coffee

I have been under a few vehicles running up to and beyond 60 mph. Diffs are noisy when they arent under load. Scary too, when asshole boss holds it to floor.I have a tool, chassis ear. Microphones on clamps and leads go into cab. They plug in a box, selectable and listen through headphones. Can hear brake pads riding on rotors. Sensetive enough.