You got me on that one...if I look at all of the parts that were used, itís more about the internal parts. All the black round pieces in the top half have holes they fit into on the internal blade holder. Not sure where you would fine parts like the emitter shroud and control box.
I personally also got a replica 3 cell from The Graflex Hop for my ANH version and love that itís so close to the real thing. Feels like a ton of work for every part of you want to turn one into a ROTJ Vader.