In 1935 EMC was starting its transition from a design and marketing company to a locomotive building company; development of regular production model locomotives was occurring before they had the capability to build locomotives. Construction of carbodies for EMC demonstrators #511 and #512, and B&O #50 was contracted to General Electric's Erie, Pennsylvania works, and AT&SF #1 was contracted to St. Louis Car Company. Like most boxcabs, they initially had control cabs at both ends, a feature that would only rarely be repeated in future North American locomotives, although it would become common elsewhere. Power was provided by twin 900 hp (670 kW) 12 cylinder Winton 201-A diesel engines in each power unit, exceeding by 50% the most power that could be attained with a single engine at that time. The added "headroom" in power extended the life of mechanical parts, which was a critical issue with early diesel engines in locomotives. The units were built with AAR type B two-axle trucks. As development design locomotives, modifications were frequently made to them to overcome various teething problems; the EMC demonstrators spent considerable time in aluminum paint substituting for the units under modification.[1]
^Iron Horses of the Santa Fe Trail, E.D. Worley, Southwest Railroad Historical Society, 1965, L of C 75-39813