This engine is modeled after the GE 44 ton switcher locomotive. Why 44 tons, you may ask? I give you the answer from the Wikipedia article on this loco type:
This locomotive's specific 44-short ton weight was directly related to one of the efficiencies the new diesel locomotives offered compared to their steam counterparts: reduced labor intensity. In the 1940s, the steam to diesel transition was in its infancy in North America, and railroad unions were trying to protect the locomotive fireman jobs that were redundant with diesel units. One measure taken to this end was the 1937 so-called "90,000 Pound Rule" : a stipulation that locomotives weighing 90,000 pounds (41,000 kg) – 45 short tons – or more required a fireman in addition to an engineer on common carrier railroads. Industrial and military railroads had no such stipulation. The 44-ton locomotive was born to skirt this requirement.
The loco is dual directional, and doesn't have much to differentiate between the "front" or "rear" expect for the air horn and exhaust stack on one end in real life. My LEGO model lacks these, so it's only way to tell which is front is by the headlights: clear for front, red for rear.
I am going to name this loco WFP number 7007. (WFP stands for Wabash Frisco & Pacific, which is the name of a 12 inch gauge ride-on railway in St. Louis, MO.) They don't have a real 44 toner there, but do have a Fairbanks Morse H10-44 (number 704) in the same color scheme, so I made this engine as a companion to the H10-44.
EDIT: Build updated on 3/14/17 with a better 44 ton GE unit, courtesy of Henry Durand over on Facebook's LEGO Train Fan Club. Thanks Henry!