During World War II, the armed forces of many countries used the C-47 and modified DC-3s for the transport of troops, cargo, and wounded.

In response to proposed changes to the Civil Air Regulations airworthiness requirements that would limit the continuing use of these aircraft, Douglas offered a late-1940s DC-3 conversion to improve takeoff and single-engine performance.

There was also a new square tail fin with a large dorsal fillet that was 1 ft (30 cm) taller than the DC-3's to compensate for the increased torque from more powerful engines.

[5] The changes fully met the new FAR 4B airworthiness requirements and up to 38 passengers could be carried, with increased speed to compete with newer airliners.

[4] Several factors led to the DC-3S being rejected by the airlines: During the later part of World War II, the United States Army Air Forces ordered a 21 seat VIP transport version of the C-47B and Douglas delivered 17 during 1944/45.

[3] Having failed to sell the DC-3S to the airlines Douglas offered a 21 seat VIP transport version with a similar configuration as the C-117B to the USAF and was evaluated under the designation YC-129, later redesignated YC-47F.

Unlike the USAF the USN ordered Douglas to convert 100 existing R4D-5s, R4D-6s, and R4D-7s to the same configuration as the R4D-8X and given the designation R4D-8, which was later redesignated C-117D in 1962.