Did MF tractors built for military contracts have a different naming convention than the farm tractors?
Military or Government tractors generally carried the same model number as the regular models they were derived from.
For example the Massey Ferguson 40 is one of the industrial versions MF produced during the period when 200 series ag tractors were being produced. This expanded line of industrial tractors was based on agricultural models with no reference in the model number to the ag model the tractor was derived from. This group of tractors included some models that used the same sheet metal as the ag tractors, but added features like a foot throttle, heavy duty front axles, mounting for a front mounted hydraulic pump, etc as well as those with a squared hard metal industrial hood and grill, and front end .
These industrial model numbers are the source of a lot of confusion when it comes to purchasing parts today as the Massey Ferguson 40 is often confused with the Ferguson 40, Similar problems exist with the Massey Ferguson 20 and 30 which are often confused with the Ferguson 20 and 30. The MF-40 married the engines, and front section of an MF-230, 235 or 240, and connecting it to the rear axle assembly used on tractors like the MF-255 and MF-265. The heavier rear axle assemblies were preferred by some customers for backhoes. The result in the case of the MF-40 is a 3 cylinder engine mated to a heavier rear axle assembly.
MF similarly produced a series of industrial models using the same hood and grill sheet metal as their 100 series ag tractors, but with features like a foot throttle, and heavy non-adjustable front axles. The model numbers for these tractors have no relation to the ag models they are derived from.