After the H-10-44 switcher, Fairbanks-Morse introduced the first road switcher in 1947. Here, too, not only was a variant of the same opposed-piston diesel used, but also again the exterior design by Raymond Loewy with rounded shapes. They were optionally available with a steam boiler so that they could also be used in front of passenger trains.

The first model was the H-20-44, the designation standing for 2,000 hp and four driven axles out of a total of four. The engine here had ten cylinders and its output represented a top value for four-axle diesel locomotives. The cab was located at the end of the locomotive, whereby the short front end was omitted. A total of 96 examples were made between June 1947 and March 1954, all of which went to US customers. For cost reasons, a simpler form of the locomotive body was chosen for the last locomotives, which used fewer curves. A six-axle variant H-20-66 was planned, but was not realized due to a lack of orders.

Three months after the H-20-44, production of the H-15-44 started, which featured an eight-cylinder, 1,500 hp variant of the engine. It also now had a short hood, as found on other road switchers. 35 examples had been delivered to US customers by 1950, when production switched to the H-16-44. With an output increased by 100 hp, 209 units were delivered to US customers and another 32 were exported to Mexico. In addition, 58 examples were built at the Canadian Locomotive Company, which were only intended for the Canadian market.