Introduced in July 1945, a total of 1,111 F3A units and 696 B units had been built for virtually every major in the US by the time production ended in February, 1949. These locomotives continued to serve in main line and secondary service on railroads across North America into the 1970s.

InterMountain?s models of the F3A unit and the cabless booster ?B? unit captures in exquisite 1:160 detail all the exterior details found on the so-called ?Phase II? units ? large 45-degree number boards, full ?chicken wire? screens on the sides of the A unit body, either ?Passenger? or ?Freight? pilots, and tall or short rooftop radiator fan shrouds, all depending on the road name and number.

The InterMountain F3s feature road specific details such as high or low rooftop fans, steam generators, horns, dynamic brakes, cab interiors, and single or dual headlights with ?Golden White? LED headlamps to provide the most realistic light possible. Each unit comes completely assembled and decorated in multiple road numbers with each release, making it easy for the modeler to quickly build up his or her roster. (Note: some railroads didn?t paint legible numbers on their B units, in those cases the models are listed as ?No Number?. Also some railroads didn?t roster B units. In those cases there is no corresponding B unit listed.)

Other features of these fine models include laser-sharp painting and lettering, authentic colors, individual wire handrails for strength and realistic appearance, body-mounted Micro?Trains? couplers, and etched metal ?chicken wire? screen for the ultimate in scale appearance. These fine locomotives feature smooth performance, great pulling power, and can easily be converted to Digital Command Control by swapping out the factory light board with decoders from both North Coast Engineering or Digitrax, two firms known for their outstanding DCC products.