I have been fixing up my 77 F150 since I got it in January and it’s really starting to look nice! I love this truck, but I have noticed a clunk sound when I put it in reverse and also a same if not similar sound when I’m driving and slow down. It makes a clunk sound when it shifts to a lower gear, (automatic). Now, I was thinking it was a U joint at some point and crawled under there and started to grab them and see if there was any play in any of the spots but found no play. I checked it a few times, thinking well it could be just the point the U joint stopped and that would explain no play but after a few times of crawling under I still never found any.