While not the most famous "M", the John Deere Model M deserves a look
When looking back on the farm tractor world, the first "M" to come to mind must in fairness be the classic Farmall M. But there was another "M."
Introduced in 1947, the John Deere Model M was the first John Deere with a vertical valve-in-head engine. (The "L" series and Dain were valve-in-block.) Considered a one-row tractor, the "M" used only regular gasoline. It was the first Deere with position-responsive hydraulic control of integral implements and with a "Quick-Tatch" arrangement for rear-mounted tools.
The John Deere model M was also the first Deere with an adjustable steering wheel and featured airplane-type hood and grill fasteners (a WW II development for quick servicing of airplanes.)
For the first time with Deere tractors, the side-mounted belt pulley was omitted. A rear-mounted belt pulley was an option.
The rugged two cylinder distributor-ignition engine produced 20.45 observed belt (read PTO if you wish) horsepower on the Nebraska test. Rather surprising considering the tractor's slim, trim, relatively small size. Its styling, common to John Deere tractors of that period, was sometimes referred to as "clean-cut styling."
The engine and power train of the "M" were incorporated into three variations in 1949. One was the "MT," a tricycle two-row version; another the "MI," a highway mowing tractor; and the "MC," the first Deere-designed crawler and the beginning of Deere's industrial yellow line of today.
In 1953 the "M" became the "40." The "M" pictured above spent its working years in Ohio. It "migrated" west to Iowa in 1982.