Apart from a 1986 copy of Jedi, my knowledge of the pre 1988 versions is very patchy.
I have, if you're interested a 1987 version of ANH, a copy of Empire from 1984 and probably the same version of Jedi that you have. All appear to be part of a rental video library collection.
If you want I can stick these in the mail and send them to you for comparison tests? I can't do it myself as I don't have a VCR.
Let me know
