The song Different Drum, by the Stone Poneys, was released in September of 1967. It reached the top 20, topping out at #13 on the singles charts.
The Stone Poneys were a folk rock trio that formed in Los Angeles in 1964. Their singer, Linda Ronstadt, went on to huge success in the 1970's. Guitarist Kenny Edwards would continue to work with Ms. Ronstadt.
The guy who penned the tune in 1966 would also go on to fame and fortune. Mike Nesmith, who was the sole son (and heir) of Betty Nesmith, who invented White-Out, would go on to be one of the Monkees, and later become a movie producer ("Repo Man").
The song is one of the few pop songs I can think of that has a harpsichord (Richard Harris' "Macarthur Park" comes to mind.