When the truck is in park and running no problem, no sounds but when pull it in drive it starts a sound like rocks tapping or motor mount vibrating, you can put your hand on the transmission tunnel and feel the vibration, which taps and vibrates every few seconds, it is not very loud nothing like I have heard on some of the YouTubes took the inspection plate off flex plate bolts are tight, could not see any cracks. Does that sound typical for a bad flex plate or could it be something else in the trans. It s a 2000XJ with 72k miles

 

It can still be the flexplate. The cracks are usually hairline around the bolt holes. I couldn't see my cracks until i got it on the bench with a magnifying glass.