i dont remember where i saw this but a while ago on a sw site i saw freeze frames from ROTJ where vader actually disappears right in front lof lukes eyes after he takes off his helmet. It showed one frame where he passed away and then a few more frames after as he faded away like yoda did. Supposedly this was gonna be the original ending for ROTJ but lucas for some reason changed his mind. The question everyone wants to know however, is why????