Haven't heard Syl Johnson's version, but it is probably real good. Al wrote many songs and many people did them, kind of like a black Bob Dylan. Probably most versions of his songs are pretty darn good.
Al did a song called,Have You Been Making Out OK? that was covered by Quiet Elegance,a female studio group from his record label.Beautiful tune.I saw him at the Cow Palace in 1972,on a bill with Smokey and the Miracles and The Whispers.