The Undisputed Truth signed photo autographed by Joe Harris, Billie Rae Calvin, and Brenda Joyce Evans.4x4 inches The Undisputed Truth was an American Motown recording act, assembled by record producer Norman Whitfield as a means for being able to experiment with his psychedelic soul production techniques.[1] Joe "Pep" Harris served as main lead singer, with Billie Rae Calvin and Brenda Joyce Evans on additional leads and background vocals.