When what we know today as the Models “50” and “60” were in development, they were still going to carry the “B” and “A” designations, respectively. Later it was determined that numbers would be used for the model designations. To set the matter straight, the first advertising literature showed the new tractors to be “SUCCESSORS TO THE FAMOUS MODELS ‘A’ AND ‘B’.”

This experimental Model “40” Tricycle has a designation decal that reads “MTA.” This was prior to the decision to go with numbers instead of letters for the new tractors being introduced in 1952. The implement is an experimental two-bottom, 3-point-hitch plow.

Even as the last of the “Lettered Series” Row-Crop Tractors was to be introduced — the Model “MT” —both Deere engineers and Deere senior management were beginning to plan for the future. Although Henry Dreyfuss had done a masterful job of carrying the Art Deco styling of the “A”, “B”, and “G” Series Tractors over to the “M” Series, by the time the first “MT” rolled off the assembly line on December 21, 1948, the styling, though still well-accepted, was beginning to to look somewhat dated. By that time, a number of John Deere dealers had been give a glimpse of the future, having seen photos of the crisp new styling of the soon-to-be-introduced standardtread Models “R” and “AR”, and the Model “AO” Tractor. No doubt some of them wondered when the row-crop lines would adopt this styling.

In 1949, in high-level meetings, senior management was trying to decide the future of the entire John Deere Tractor line. There were those, including Deere president C.D. Wiman, who were in favor of scrapping the very successful current line of two-cylinder tractors, and beginning the changeover to multi-cylinder tractors starting with the breadand- butter row-crop models. There was resistance this proposal, led mostly by L.A. “Duke” Rowland, who was in charge of all tractor production. He argued that though some change would be needed, the two-cylinder tractors were still selling well, the company had spent millions of dollars and well over a decade developing the Model “R” Diesel, and a major change in the Deere tractor line — such as scrapping the current models and replacing them with four-or-sixcylinder models — couldn’t be done with less than nine months of downtime. To Rowland, this was unacceptable in a seller’s market that was keeping both Waterloo and Dubuque running at full capacity. On the other hand, the chief engineer of the Dubuque Tractor Works was all for the proposed change. The design of the Model “M” Series Tractors was such that adding a four-cylinder engine would be a minor problem, and could be done with minimum downtime. In the end, a compromise was reached; while work could begin at both Waterloo and Dubuque on engines with more than two cylinders, the current line of two-cylinder tractors would be upgraded, with the best-selling models receiving the upgrades first. So, beginning in 1949, a plan to upgrade the current line of row-crop tractors would get underway, and experimental tractors would be in the field by 1950.

At Waterloo, there were a number of significant improvements that could be made for a new line of tractors. A problem that had nagged the two-cylinder engine since the days of the Waterloo Boy was that, due to the firing sequence of the two-cylinder engine design, one cylinder didn’t receive the same charge of fuel and air that the other did. This was compensated for by making the air-fuel mixture richer than it should have been, thereby sacrificing maximum