It never got as far as just being recorded at the guy's audition for Motown as far as I'm aware, studio test pressing only. Never pressed other than that not even for filing purposes, thats probably why the above you mention haven't picked up on it. It is genuine and not the thing that was suppoosed to be for Musicor or that terrible 70's job that is knocking about. It really is bad and Berry Gordy probably couldn't get the guy out of the studio's quick enough and then destroy all traces of the attempt at a vocal
As for not hearing it, John has played the thing at the 100 Club.
Trust me Tone, stay on the unbelieving side, you DON'T want to hear it