My transmission makes a clang sound when shifting into reverse(hot or cold). I also have a growling sound from under car while coasting at 40mph and higher,sound goes away if I put it in neutral. Other then that transmission shifts perfect.(transmissions stock rebuilt two years ago)

2000 grand prix gt slp headers and cat sd ram hood and airbox 180,000 miles
Had rebuilt engine and transmission installed two years ago. And two steering racks.