Fred Haise went on to fly some of the Enterprise test flights in the late 70’s. One of my co-workers was a technician at JSC at the same time, and says they had a meeting after one of the drop tests to talk about the landing gear. I guess there was some concern about how the landing gear held on return. Anyway, Haise noted that the tests were all done with an empty orbiter, but wondered about the safety of the landing gear if the orbiter returned with cargo. Someone ran the numbers, and discovered that the extra weight would break the nose gear. Haise left the astronaut corps shortly after...
Ken Mattingly went on to command two Shuttle flights, including the last “test” flight in 1982. There is a picture that shows up on FR every so often of a shuttle crew saluting President Reagan, with Reagan wearing a pinkish suit — Mattingly is the commander saluting in those pictures.
I've often wondered if any of those Apollo guys felt a bit of a letdown being reassigned to the shuttle program. I mean, I'm sure they are professionals and were glad to have a chance to serve, and there was important work to do, but somehow LEO missions don't have the glamor and excitement of going all the way out to the moon and back. Don't get me wrong, I think the technology developed for the shuttle, especially the hydrogen-fueled main engines, is pretty amazing stuff. But going to another world is, well, out of this world in terms of wonder.
John Young is another former moonwalker that became a shuttle jockey, along with Mattingly. Haise did the atmospheric glide tests but I don't think ever went into orbit again. Any others? I can't think of any offhand. Joe Engle trained for Apollo missions but never flew in that program. I guess he'd be another.