As the Box Tops, they entered the studio under the guidance of producer Dan Penn to record Wayne Carson Thompson's song "The Letter". Though under two minutes in length, the record was an international hit by September 1967, reaching the Hot 100's number-one position for four weeks, selling over four million copies, earning a gold disc, and receiving two Grammy Award nominations. During 20–27 October 1967, "The Letter" and The Hombres' "Let It Out (Let It All Hang Out)" were 1-2 on the WLS (AM) Silver Dollar Survey, marking a rare quinella involving two brothers of the same family (the Cunningham brothers), each in a different top 40 act.