I'm pretty sure its on the 1997 SE 2-disk set. ESB had a lot of really good music cues that were wisely taken out of the film by Irvin Kershner after being scored because he felt that the dramatic tension worked best without them. The probe droids entrance at the opening had a more bombastic cue, there was music during the imperial walkers first being spotted, music during Luke and Vaders final duel and music during some of the dagobah scenes. I am guessing it is from one of these cues. The music is actually very well done, and the scenes still play well with the music in them, just in a different way from what Kershner got in the final film with a silent background.