Sometimes,not enough pin weight will cause more noise also,if your fresh and or gray tanks are in the front,try filling them and go for a ride to see if it changes,when all my tanks are empty,sometimes I will get a little clunk,but 90% of the time it's quiet,and I do not feel or hear any clunk.Are you using a Teflon disc on the pin box?
2011 Palomino Sabre 31RETS,5th Wheel,Triple Slide,4000W Onan Genset
2006 Super Duty,XLT, V10, 6 Speed, 4.10, Tow Command, Tow Pkg. 4X4,Dual Exhaust,K&N,Reese 15K,Air Bags