Shop Torque King for parts, tools, and shop manuals specific to 1966-1975 Ford F100 Dana 21 direct mount, single speed transfer cases.
The Dana 21 is a single speed gear drive transfer case with a input shaft mounted on the transmission output shaft that was only used in Ford F100 1/ ton 4x4 pickups from 1966 to 1976. The Dana 21 was the only F100 transfer case option for the 1966-1972 model years. Starting with the redesigned 1973 F100, the rugged NP205 2 speed transfer case was optional with certain drivetrains and the full-time NP203 2 speed transfer case became an option in 1974. The Dana 21 was discontinued after the 1976 model year and neither Ford or Dana provided much parts support after that.
The Dana 21 is not a very strong transfer case and the lack of low range gearing severely restricts the off road capability of the F100. On the plus side, it is a simple, 3-shaft transfer case that was adequate for occasional use with the low-powered engines and small tires of the stock truck.
