FM H-10-44, Class FS10
The FM H-10-44 was a yard switcher produced by Fairbanks-Morse from August, 1944–March, 1950. The units featured a 1,000-horsepower, 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. Many H-10-44s received modifications that increased their horsepower rating to 1,200 hp.
The Raymond Loewy-designed carbody featured a slanted nose, sloping hood lines, and (considered to be its most distinguishing feature) a protruding roof visor mounted on the rear of the cab. These styling cues were carried through to the H-10-44's successor, the FM H-12-44, until September 1952 when the exterior design was "Spartanized" to reduce production costs.
A total of 195 units were built for American railroads.
| Road Numbers | Qty | Delivery | HO Scale Models |
| 5980-5986, 9184-9199 |
23 | 6-9/48 | Walthers (5980, 5986) |
| 9288-9299 | 12 | 3-4/49 | Life-Like Proto 2000 (9291, 9298) |
| 9080-9099 | 20 | 7-11/49 | Walthers (9086) |
FM H-12-44, Class FS12 / FS12m
The FM H-12-44 was a yard switcher produced by Fairbanks-Morse from May, 1950–March, 1961. The units featured a 1,200-horsepower, 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 60 miles per hour (97 km/h).
A total of 303 units were built for American railroads, 30 were manufactured (between August 1951 to June 1956) by the Canadian Locomotive Company for use in Canada, and 1 unit was exported to Mexico. Initially, H-12-44s were visually indistinguishable from their predecessor model, the FM H-10-44. However, beginning in September, 1952 the Raymond Loewy design elements were removed as a cost-saving measure: 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 possibility of battery explosions. None of the units were produced between May and October 1956, after which time the carbodies were shortened by some three feet and outfitted with a deeper side skirt.
| Road Numbers | Qty | Class | Delivery | HO Scale Models |
| 8711-8723 | 13 | FS12m | 11/52 | |
| 8708-8710 | 3 | FS12 | 2/54 |