My '10 XLT 4x4 has the clunk too. I have a one piece driveshaft, but everyone else seems to have the two piece? The dealer still did the TSB for greasing the slip yoke and it drove butter smooth for about 600 miles and now the clunk is coming back.

What exactly is the problem? Are the male/female connections too loose causing the play? Can buying a better slip yoke that fits better stop the clunk? I read somewhere on a Ford forum that a guy took a thick rubber hose and basically jammed it between the threads of the male and female components and it stopped his clunk. I plan on keeping this truck to over 200,000 miles and I'm afraid that wont happen unless there's a permenant solution for the clunk. Our 01 Expedition has over 140k on the clock and runs perfect