97 XJ, I can feel occasional taps/knocks in the floor board under my feet at idle?

What is this that I'm feeling? It's not all the time, it's almost random. Very light taps, you almost have to have a mind for noticing little things to realize it's there.

It's most likely in the exhaust system. Look at both the exhaust mounts and the trans/motor mounts.

Could be the exhaust contacting the trans cross member? The exhaust can sag with age, the trans mounts get old, as do the motor mounts.

A quick test is to try and stick your finger tip between the (old) exhaust and the rear of the trans cross brace. If you can't get a finger tip in there, it is likely to be a problem.

Thanks! I probably do need to change both motor and tranny mounts asap. 190k miles now. New to me but I've put about 5k on it already