Besides being impressed with the young guitarist's playing, Stax Records president Jim Stewart saw professionalism and maturity beyond Cropper's years. When American Records founder Chips Moman left Stax, Cropper became the company's A&R man. He became a founding member of the Stax house band Booker T. & the M.G.'s, along with Hammond organ player Booker T. Jones, bassist Lewie Steinberg (who was replaced by Donald "Duck" Dunn soon thereafter) and drummer Al Jackson Jr.. As a house guitarist, he played on many recordings such as "(Sittin' On) the Dock of the Bay," co-written with and performed by Otis Redding and Sam & Dave's "Soul Man" on which he was mentioned by name. When Cropper played on the song's remake by the Blues Brothers, lead singer John Belushi again mentioned Cropper. On the early Stax recordings, Cropper is known to have played a 1956 Fender Esquire and later used a blonde Fender Telecaster.