Clunking noise

I saw a note on eTrailer that mentioned one other thing: high hitching. When you hitch up the bottom of the king pin shout be 1/2 to 1 inch below the skid plate. If you hitch up with the king pin bottom higher that that it's called high hitching. I know that can also cause hitch damage.

They also mention worn king pin but that should not be a problem in your case with a new unit.

Teflon Lube late is great for replacement of having to grease hitch plate and king pin plate and could cause the clunking

Other causes....

King pin and hitch jaws/bar....slop (king pin moving back/forth inside hitch)
King pin hanging up on jaws/bar......lack of grease on king pin and it can bind
Hitch head bolts.....loose not properly torqued (Head moving inside frame/supports)
Capture plate/wedge loose (depending on brand of hitch)
Hitch rails....not secured/properly torqued (Hitch moving)

5vr Nose High.....to light of pin weight

If you are towing with that 2002 F350
Last item should NOT be an issue as the dry pin weight is 2950
Dry weight of that 5vr is 2000# MORE than what your truck is rated to tow (Dry 15,300 vs MAX Tow 13,200) and the GVWR is almost what the GCWR is (19,500 GVWR vs 20,000 GCWR)

You REALLY need to go across some CAT Scales and get your weights.

It's called chucking. Just from curiosity do you have a Reese hitch. A teflon ring might help but maybe not. Chucking is more or less unknown with better hitches.

It is the pin moving in the hitch coupler. Go to any RV parts store and get a Teflon ring that goes around the pin. Problem solved.