American diesel locomotive
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The FM H-12-44 was a switcher locomotive produced by Fairbanks-Morse from May 1950 until March 1961. The units had a , six-cylinder opposed piston engine prime mover, and were configured in a B-B wheel arrangement mounted atop a pair of two-axle AAR Type-A switcher trucks, with all axles powered and geared for a top speed of .
Of the 336 H-12-44 locomotives produced, 303 were for American railroads, 30 were made between August 1951 to June 1956 by the Canadian Locomotive Company for use in Canada, and one was exported to Mexico. 
H-12-44s were visually indistinguishable from the predecessor FM H-10-44 until September 1952, when the Raymond Loewy design elements were removed to reduce production costs. Cab lines were squared-off, the slanted-nose styling was discontinued, and the roof visor was eliminated. The following year, the fairing over the battery box was removed and louvers added to reduce the chance of battery explosions. Production paused from May to October 1956, after which the carbodies were shortened by some three feet and outfitted with a deeper side skirt.
Sixteen intact examples of the H-12-44 are known to survive, all of which are owned by railroad museums or historical societies.
Preservation.
Several examples of the H-12-44 model have been preserved around the U.S. and Canada.