I have an 04 rubicon with 20000 on it and keep hearing what I think is the tailpipe rattling but when I check it ,it seems sturdy. suggestions?

 

Check the heat shield above it. If not loose check the cat. I had both probs with my TJ at different times over the course of owning it. After the heat shield was taken out, years later I had another rattle and it turned out that a chunk of catalyst had broken off internally and was tumbling around inside like a lotto ball. If so, only matter of time before that piece tumbles it's way down the shoot and chokes out you rig thus winning yourself a car that won't run. You saw the banana in the tailpipe trick on Beverly hills cop, right? Yeah, just like that. :-)