Undercarriage rattle

[jawon]

Taking a very wild stab here.

Took the truck on a gravel road. Went over a few potholes. Now there is a rattle underneath, sounds kinda like a rock rattling around somewhere. Pretty persistent, but not rhythmic or caused by any specific action like braking, changing gears, etc. Nothing obvious is loose. Everything else feels/sounds fine. Mechanic couldn't find anything.

I know this is a longshot, but any clues what this might be?

 

[Kenneth S]

Sounds like my truck used to, found out that the ceramic inside the catalytic converter started to breakup, it makes the "rock rattling around" noise you hear but can't find.

 

[Mark_88]

This could also be a heat shield that broke loose or got too close to the muffler...had that on my Tempo and just about drove me nuts...well...it would've been a short trip anyways...there is a heat shield over the muffler on the passenger side...check to see if it's loose...