The original 1967 version of "Ain't No Mountain High Enough" was a top twenty hit. According to record producers, Terrell was a little nervous and intimidated during the recording sessions because she did not rehearse the lyrics. Terrell recorded her vocals alone with producers Harvey Fuqua and Johnny Bristol, who added Gaye's vocal at a later date. "Ain't No Mountain" peaked at number nineteen on the "Billboard" pop charts, and went to number three on the R&B charts. "Billboard"'s original review of the single stated "Chalk up another pulsating fast smash for Gaye with his new partner Tammi Terrell. The electricity of the duo combined with the blockbuster rhythm material grooves all the way."