The first significant upgrade to the 310 line came with the 310C of 1959, which introduced more powerful 195kW (260hp) IO-470-D engines. The 310D of 1960 featured swept back vertical tail surfaces. An extra cabin window was added with the 310F. A development of the 310F was the turbocharged 320 Skyknight, with TSIO-470-B engines and a fourth cabin side-window.

The 310G introduced the 'stabilatip' tip tanks, while the 310K replaced the rear two windows on each side with a single unit. Subsequent significant developments include the 310Q and turbocharged T310Q with redesigned rear cabin with a skylight window, and the final 310R and T310R, identifiable for their lengthened noses. Production ended in 1980.