If I am not mistaken, you can here Barry McGuire loud and clear on the NCM's "Green, Green"-

Not only did Kenny Rogers come from the New Christy Minstrels, all but one of the other four in the First Edition did, as well. He also sang with the Kirby Stone Four. I was always amused by the fact that "I Just Dropped in to See What Condition My Condition Was In" was always left of of those Kenny Rogers Special TV offer compilations--