Thunking sound from powertrain
 

I have a '98 Cherokee Limited with 130,000. On the highway sometimes I hear a thunk or series of thunks from under the car, they usually happen close together then go away. I can make the sound happen if I switch lanes to the right or the highway turns to the right slightly. I can feel it on the passenger side foot well near the tranny and all the way back if I put my hand on the drivetrain well in the back seats. It only seems to happen at higher speeds 40-70 mph. It doesn’t seem to affect the car at all but the sound does worry me. I checked the front end and everything is nice and tight. Anyone have any experience with this issue?



Thanks for your help.