The 1930 10-A design study only went as far as a wind-tunnel model with four engines, two of them pylon-mounted in a tractor-pusher configuration. The design continued in the 12-A of1931. The 12-A was a modified 10-A design with three engines (planned for 1000hp Hispano-Suiza + two 575hp P&W Hornet). Not built, but design elements went into the 14-A.

The 1932 Ford 14-A, NX9660, involved elements from the 10-A and 12-A designs, and was the last of the Ford Tri-Motors. Pullman-style seats converted into berths in the four main, climate-controlled, eight-passenger compartments. Wing motors, with four-blade propellers, were buried, and the third was pylon-mounted atop the fuselage; compressed air starters.