I was always under the impression that "Hail to the Chief", the second-season opener of CAR 54 WHERE ARE YOU, had been withdrawn from syndication. In this episode, Muldoon (Fred Gwynne) gets a back attack of nerves when assigned to escort the JFK motorcade through downtown Manhattan. I was under the impression that this episode was yanked from the package after the Kennedy assassination.
However, I recently saw a syndication copy, in which several newsfilm shots of JFK were replaced with pictures of LBJ (also, the President's actual name is never mentioned, presumably so that the show would never "date"). Thus, it apparently was syndicated--but not in the Milwaukee area, nor was it part of the manifest when Nick at Nite ran the rest of the CAR 54 episodes back in the early 1990s.