Yep it got the Dolby Stereo in the 70mm blowup, but has since been MIA. Due to the usual constraints and producer's dislike for added costs, I don't think the blowup would have differed greatly if at all from the 4 track master. There also vague references and rumors of previous films getting a 70mm blowup such as YOLT (Japan only), TMWTGG, Spy, Moonraker. I'd have thought it likely for Thunderball to have received a blowup but probably not due to the harried post-production schedule.

All this aside one interesting tidbit from John Glen's autobiography: they did a stereo multi track mix for OHMSS!!! He goes into great detail about how it was discovered the premiere theater was only wired for mono and how they had to take apart the fake cabinets to actually install true stereo rigs along with additional speakers for what I presume is the rear channel.