http://www.maverick-media.co.uk/movies/thx_1138_1971/changes_001.html
It's funny though, the THX re-do is often very clever and subtle (not always of course) and clearly had more thought put into it than any of the SIX (!) fricking passes at redoing a Star Wars movie (97 and 04). If both versions had been included and the changes acknowledged in the doc, like Blade Runner, we'd have a really great release.