In particular the year of the eclipse is not evident - but one can read that the image was taken from a KC-135 airplane over the Atlantic near South America. According to this article (page 5) and this one (page 6) the KC-135 astronomy program covered 6 eclipses from 1965 to 1980 - and
I may add that I actually once met Ruff in a professional context ... in 1991 at the Kunstverein in Bonn, Germany, where he had an exhibition before becoming a celebrity showing the "Sterne" series. Together with a friend we created an astronomy-didactical show in which we tried to convey the depth in these huge prints of ESO sky images that contained stars, galaxies but also occasional satellite tracks. I don't recall much but one detail: I had prepared a square meter of paper with a square millimeter marked on it to demonstrate what a million - being the difference in area - meant. We couldn't come up with a means to demonstrate a billion, though ...
ADDENDUM: Airborne eclipse expert Glenn Schneider has pointed out in personal messages that the 1966 TSE is a much better fit when a KC-135 also observed - several text fragments that can be deciphered match actual information on that flight. "The name of the place is not very legible," says Schneider, but it sure looks like Rio Grande which "is on the coast (not too far away) and is very close to 240 miles from greatest eclipse" - where you logically would fly with a research aircraft. And from what one can read the plane was "240 miles southeast of" said town.
Schneider also points out that while the 1973 TSE was visible low from parts of South America, that's a long way "to where the Concord flew across Africa! You are right that in 1973 the guys in the KC-135 watched the Concorde streak by overhead at 55,000 ft - but they were over Africa, not South America or the nearby coastal waters. Finally I will add, the corona in that picture, though not a very good picture, just does not look like the 1973 corona. I did not see the 1966 eclipse as it pre-dated my eclipse chasing started in 1970, so I cannot comment on that directly. But I did see 1973, and that just doesn't look the same..."