Was the optical track on PSB really a different mix? I know that was the case for PG, but I thought the mono on PSB was just a folddown of the stereo. Honestly I can’t remember.
I’m also assuming there never was a mono mix of ROTJ… (right?)
That’s not 100% for certain. There were still a lot of theaters rocking mono well into the '80’s.
80’s… try 90’s here. We had a total of 7 Mann screens in two buildings. 6 of them mono until they closed. I ended up with the screen from one of them, but had to throw it out because it was cracked. That was after 90 and the 4 plex closed later. We also had a two plex with a mono and stereo theater and I remember I saw Blade Runner in 1992 in the mono theater and Gone With the Wind in the stereo theater. But I believe that along the way all the projectors became stereo compatible. That was the goal of the Dolby Stereo process… whether you have one speaker, two, or full surround, one print for all.