There are clues in the different versions that we can trace back. The first one to land on is the production of the foreign language versions back in 1977. Aside from the changes in audio and the different opening crawl, the Definitive Collection/Faces/2006 bonus discs are identical. So from late 1977 to 1985 when that interpositive was made, no changes were made to the film, except for the opening crawl. And that was restored for the 2006 bonus disc. And the changes to the audio made for the audio for that version were all taken from the mono mix. So the 2006 bonus disc is the closest we have to the general release of the movie.
The JSC has 3 shots that were changed. When the Star Destroyer is shooting at the Falcon as it leaves Tatooine, the exterior composite shot of Luke, Han, Leia et al. arriving on Yavin IV, and the shot of the rebel fighters taking off for the Death Star. So far, only one of those shots in one single 35 mm print has been found. Otherwise those three shots on 35 mm match the 1985 interpositive. That includes the Technicolor prints which we know were made in 1977.
We also have something intriguing in two other sources. We have the bootleg widescreen that Moth3r shared with us and the English 16 mm print that Puggo captured and shared as Puggo Grand. These two prints are unlike any others. They have the original crawl, a completely different end credits, and those same 3 shots found in the JSC. Also, both Moth3r’s bootleg and Puggo Grand are mono, but it isn’t the mono mix, it is a mixdown of the stereo track.
When you put the pieces together, those 3 FX shots must have been changed sometime between the May 25 premier and when the Technicolor prints, foreign language prints, and the general release prints we have had access to were made. Same for the end credits. All the English language prints before the Definitive collection used older interpositives and they all have the same 3 flawed FX shots (if you watch them you can see the flaws and see how the replacements are the same but improved), the 81 crawl, and the revised end credits. Movie studios and distributors think nothing of mixing and matching prints. My guess is that the error in the end credits was caught early and at least one print was made before the FX shot was changed in the same reel. That would explain the print that the English and Japanese home videos were made from, all from prints in Fox’s possession. It has several other notable flaws as well. Then the 3 FX shots were replaced, probably when they did the mono mix. And everything after that is identical until the 97 SE edits (when 2 of those FX shots were replaced again.
So if you want to see the original May 1977 version, check out Moth3r’s bootleg and Puggo Grand. If you want to see the movie as most people did, check out 4K77. JSC is a hybrid of those versions with the added tractor beam line from the mono mix (why only the one change, I do not know). The 2006 bonus disc is the closest to the July 77 print with mono that we have had in an official release.