In his role as Duke Slater on Gomer Pyle, U.S.M.C., Schell's character was cast for three seasons as a Marine private and best friend of Gomer Pyle. Schell left for a season to star as a disc jockey in his own sitcom, Good Morning, World. He then returned to Gomer Pyle, U.S.M.C. as a corporal for its fifth and final season. Schell played his Duke Slater character as streetwise, compared to Pyle's bucolic background as portrayed by Jim Nabors. Upon returning as a corporal, Slater acted as more of a mediator between Pyle and Sgt. Carter, portrayed by Frank Sutton, than as Pyle's buddy.