Major Party Nominees who voted for Opposite party in later election

[E-Dawg]

Examples that come to mind:
John W. Davis (1924 Dem Nominee) voted GOP for President in 1936, 1940, and 1944
Al Smith (1928 Dem Nominee) voted GOP for President in 1936 and 1940
George McGovern (1972 Dem Nominee) voted for Gerald Ford in 1976 (this one still makes no sense to me)
George HW Bush voted for Hillary Clinton in 2016

Are there any other examples? I know that Grover Cleveland supported 3rd party candidate John Palmer in 1896, but I don't know who he supported in 1900.

[E-Dawg]

Wouldn’t surprise me if Eisenhower secretly voted for LBJ in 64 or LBJ himself voted for Nixon in 72.

I agree on LBJ for Nixon, but I think Eisenhower was truthful about suppporting Goldwater since he really liked the also very conservative Reagan, advising him and supporting him behind the scenes. (https://www.washingtonexaminer.com/weekly-standard/unearthing-the-eisenhower-reagan-connection)
There's also the fact that he did an ad supporting Goldwater where they appeared together (https://www.youtube.com/watch?v=Lly3jANwMZM) which I doubt he would have done if he didn't actually support him.