I do remember that McGovern was so bad, the Teamster's actually came out early for Nixon. Even more surprising was the AFL-CIO refused to make an endorsement at all. I was too young to vote at the time (by just a few years) but very active politically. I also remember some reporter asking George Meany (then AFL-CIO boss) why he didn't run for president and he replied tersely "I don't care to step down!" He was an arrogant bustard, but he did have a small sense of humor.
This is from the Teamsters’ own web site:
“For example, in 1980 and 1984, the Teamsters endorsed Ronald Reagan for president. (Reagan was a union leader, having served as the president of the Screen Actors Guild. Teamsters union members are fixtures on the crews of television shows and motion picture sets.) In 1988, the union endorsed George H.W. Bush.”
It appears the union not only endorsed Reagan both times, but endorsed Bush the Elder in his first run as well. I didn’t remember them endorsing Bush, but I was pretty sure they endorsed Reagan.
Not that it matters all that much. I doubt we will ever see the union endorse another Republican.