I have a snapping when I put my truck in reverse. I replaced the u joints but it still has this clunk or snap. My pinion gear leaks a little and more when I am hauling my trailer with a load. So if anyone has every had this happen to there F150 let me know.

Rick Simar

Could be excessive back-lash in the pinion/ring gear. It can be adjusted out if not worn too badly.

try checking your front ujonits