The Jeep CJ-3A went to production in 1948 alongside the last of the previous generation. It shared much of the design of the previous CJ-2A but continued to improve and take on its own identity over the next 6 years until production ended in 1953.

The changes made from to the CJ-3A were varied but most obvious was the single piece windscreen as opposed to the previous split windscreen. The flat fenders were retained but the rear wheel arches were adjusted to give more legroom for the driver and passenger.

Mechanically, the engine was modified to give more reliability and the clutch and drive train beefed up to take more punishment. The engine was the Willys' 60 hp L-134 "Go-Devil" 4-cylinder 'flathead' engine that had already proved its worth up to that point. The transmission was still the Borg-Warner T-90 3-speed manual.

Production numbers improved until 1951 when it peaked at 44,158 and by the time production of the CJ-3A finished in 1953 more than 130,000 had been built. Some late on were assembled by Mitsubishi for the Japanese Police and Forestry Agency.

The company Willys-Overland was at this time bought out by Kaiser and became the Kaiser-Willys Company.