The 400 was designed as a high torque, low RPM engine that was a smaller, more efficient and lighter alternative for the big Ford 385 engines, the 429 and 460, for use in Ford's medium and large size cars. Weighing just 80% of a similar big-block, it was originally available in Ford's Custom, Galaxie and LTD lines, and in Mercury Monterey, Marquis, and Brougham for the 1971 model year. For 1972, it was also available in the Ford Torino, Mercury Montego and its variations through 1979. By the late 1970s it was also available in the Ford Thunderbird, Ford F-series pickup trucks, the Lincoln Continental, and Mark V.