Who played Jawbreaker in MASH?

In the 1970 Robert Altman movie, MASH, John Schuck played the character Capt "Painless Pole" or "Jawbreaker" Waldowski who was the resident dentist. Painless was engaged to 3 girls back home and didn't want to be unfaithful to any of them, even though he was 7000 miles away.