So far there is no fix for this problem, if you get a replacement rear end now, the noise will come back eventually. The Aviators and Navigator revised rear ends have been out for about 2 weeks now, so far so good on the ones we replaced. Of course Ford will want to have a fix for the "high dollar" vehicles, but yet the truck owners get put off till last. I constantly ask my Ford field engineer and he promises to call me as soon as he knows something further. I am about ready to file Lemon law and get and 04.....
BTW the driveshaft doesn't really fix anything, its just dampens the noise coming from the rear end. Kind of like putting a band aid on a wound that needs stitches.