Got the T-Shirt!
Mine did the same thing in just one year. I believe that the cause was that I did not tighten the upper mount nut all the way down to where it contacted the inner sleeve. ORW was not forthcoming with much help, so I contacted a local shop and the guy there gave me a set of Rancho poly bushings. I was able to fit them to the Bilstiens (they were just a bit too tall) and haven't heard a clunk since. I have been using the truck quite heavily and hard the last five weeks and am convinced that I should not have any further problems.
I just wish that the instructions with the Bilstiens had been better.