It has already been decided that the structural requirements for adding winglets that are large enough to be worth it in cruise are far to great to be economically feasible. API flight tested 14 ft tall ones last year on a -70A powered ex FedEx freighter.. .As far as the re-engine part goes, the Trent 500 is probably marginal on a 747. Boeing Airplane Services already has a master change for CF6-50/CF6-80 re-engine for the Classics and there are some flying. The Trent is a digitally controlled engine that takes massive cockpit changes to make work and in the end would eliminate the FE(Glass Cockpit, 2 seater). The CF6 can be either digital or analog so very little changes are needed in the Flight Deck. I am not sure if they keep the FE after the MOD. By the way the last airline that did this paid ~25,000,000 per airplane for CF6-50E2s. <img border="0" title="" alt="[Wink]" src="wink.gif" /> <img border="0" title="" alt="[Smile]" src="smile.gif" />