Introduced in the early 1950s, parts of this transmission’s basic design are still used in today’s models
Ford’s first automatic transmission, which appeared in its 1951 models, was referred to as the Ford-O-Matic. This basic unit was designed by Borg-Warner and would become the platform from which many later model automatic transmissions would evolve.
Developed as a three-speed automatic, the Ford-O-Matic used a cast-iron case and would normally be started in second gear. For this reason, you often see the Ford-O-Matic referred to as a two-speed, although the only actual two-speed units were produced from 1959-’64, and they had aluminum cases.
A sprag was added to the planetary assembly in 1958 so that you could select whether to start out in first gear or second, and the Ford-O-Matic name was changed to Cruise-O-Matic. They were later upgraded to the FX and MX series Cruise-O-Matics, then the single FMX transmission, and eventually, they evolved into the overdrive AOD transmissions used in the 1980s and 1990s Ford cars and trucks.
The Ford-O-Matic was manufactured in three different case sizes. It was initially offered in both small-case from 1951-’60 and medium-case from 1951-’68 (often referred to as the Merc-O-Matic); large-case versions were also used in 1958-’65 Lincolns.
The 1951-’60 three-speed models can be identified by an oval aluminum tag mounted on the left side of the transmission case just above the oil pan; 1961 and newer units have a tag on one of the oil pan bolts.
Transmission ID numbers were three digits long from 1951-’54 and started with “1P”; 1955 and newer Ford-O-Matic ID numbers were four letters and started with “P.” The ID number will tell you if you have the small, 97⁄8-inch case or the medium, 107⁄32-inch Merc-O-Matic case.
Large-case units were 107⁄8 inches from 1958-’60 and 115⁄8 inches long from 1961 to 1965. They can be found in 1958 Edsels; 1958-’60 Mercurys and Lincolns; 430 V-8 equipped Thunderbirds, and 1961-’65 Lincolns.