We had chucking noises from two locations:
1) between where the hitch connects to the hitch-rails in the truck bed. We placed spongy shelf liner between the two, and removed that noise. Unfortunately, that also insulated the ground connection (in the Fords, the ground-pin connection in the trailer plug is undersized, so the circuit completes the ground through the hitch connection), so we ran into an electrical issue (truck kept telling us "trailer wiring fault" and "trailer disconnected")... so we now put the shelf liner in 3 out of the 4 connections, and leave one bare (or we have to use jumper cables as an extra ground wire connection).
2) there is an adjustment bolt on the head of our hitch (a Hijacker) - the going recommendation is, once hitched, to tighten this bolt, then back it off 1-2 turns. If that bolt is too loose, you get a lot of chucking. If it's too tight, things rub which you don't want to rub... and we've also found, if it's too tight, it's difficult to un-hitch. So, we now loosen before un-hitching, and re-tighten before driving away, every trip.