The GE 44-ton switcher is a four-axle diesel-electric locomotive built by General Electric between 1940 and 1956. It was designed for industrial and light switching duties, often replacing steam locomotives that had previously been assigned these chores. 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 – 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 designed to abrogate this requirement. Other manufacturers also built 44-ton switchers of center-cab configuration. GE built 276 of this locomotive for U. S. railroads and industrial concerns, four were exported to Australia in 1944, 10 were exported to Canada, 10 were exported to Cuba, one was exported to the Dominican Republic, five were exported to France, three were exported to India, six were exported to Mexico, five were exported to Saudi Arabia, one was exported to Sweden, two were exported to Trinidad, 10 were exported to Uruguay, and 57 were built for the United States Armed Forces. Many remain, in service and in museums. Prime mover options The locomotives were available with a choice of prime movers. Most were built with a pair of Caterpillar's D17000 V8 engines, but three other engine types were used. Nine were built with a pair of Hercules DFXD engines; two were sold to Chattanooga Traction and seven were sold to Missouri Pacific Railroad and its subsidiaries. Ten were built with a pair of the slightly more powerful Buda 6DH1742, rated at each. The last four locomotives built had Caterpillar D342 engines, of which three were sold to Canadian National Railway and one to the Dansville and Mount Morris Railroad. Military version During the Second World War, GE produced a "Drop Cab" variant of the 44-ton locomotives for the US Armed Forces. These appeared similar to the standard 44-ton but had a lower cab for European clearances, and large boxes next to the cab, on the front right, and back