Rutgers was undefeated in the FF4 that yr too losing to MI so 3 big 10 teams! I know they werent Big10 at that timeIU’s undefeated 75-76 team beat Michigan to win the Natty. That was only the second year in which more than one team from a conference was allowed in the tourney (and even at that it was capped at 2 teams).
Prior to that you could be the 4th ranked team in the country, as an example, but if you finished second in your conference to the number one team in the country you did not get into the tourney.