Shake and Brake

2011 Offroad
When my truck goes over bumps, or across uneven road surfaces I hear a rattling from under the truck. I thought it was an exhaust hanger, or similar problem, but as far as I can tell that is not the case.

If I apply the brakes (even slightly) the rattle stops. I have been unable to identify if the sound is coming from the front, or rear units when driving. I have checked, but cannot locate the source of the sound.

Any ideas?

 

Loose caliper mounting bolts?

Possible that the anti-rattle shims on front pads came loose and are just rattling around, then when you apply brakes it squishes them in the calipers causing the rattle to stop?

Pull the rear drums and check for loose things that shouldn't be loose?

Just some crazy fringe ideas to help find it, good luck.