In fact, he didn't even run again on the GOP ticket in 1976. Bob Dole was Ford's running mate against Jimmy Carter.
I wasn't using Rockefeller as an example of anything, although I could. Giuliani reminds me of Rockefeller because he's an unacceptably moderate Republican---what they called a Rockefeller Republican back then.
As a matter of fact Rockefeller was a perennial contender for the nomination and he was thwarted by more conservative candidates every time---Nixon twice, and Goldwater in '64. (Some irregularities in his domestic life didn't help either.)
If Giuliani seeks the nomination, I'm sure the same thing will happen to him. Republicans prefer conservatives when they can get them.