The M-Series was introduced in Canada because smaller communities had either access to an only Ford dealer or a Lincoln-Mercury-Meteor dealer, but not both; a Mercury truck line offered more opportunities for truck sales.
Between 1948 and 1968 Ford of Canada used the "F" prefix for Ford and "M" for Mercury. From 1948-1950 nominal tonnage ratings were replaced by a series designation in which the numbers indicate the GVWR when equipped with tires of appropriate capacity. Each code number is arrived at by dividing the GVWR of the series by 100. Thus an F-47 (M-47) indicates a GVWR of 4700 lbs. per axle or 9400 lbs. total for front and rear axles combined, F-135 (M-135) indicates 13500 lbs., etc. Each truck series is rated to its GVWR. In 1951-52 Ford of Canada got back in step with Ford USA with F-1 (M-1), F-2 (M-2) etc. (GVWR = Gross Vehicle Weight Rating - weight of chassis, cab and body, plus payload)