Tailgate is loose
I know a couple of guys that had tailgate rattling problems on their pickups. They both removed the tailgate (easy/no-brainer) and placed pieces of inner-tube in the wells you set the bottom of the tailgate in.. Both guys eliminated the rattles/noises doing this. Easy to try. I guess you could also put a thin layer of say RTV Sealant on those same places... let dry overnight and then put tailgate back in place.


