In the thirties, the Union Pacific worked together with General Electric to create steam turbine locomotives with electric power transmission. So GE could not only use their expertise in generators and traction motors, but also in turbines. Designed to be used in pairs, each pair was required to haul a train of twelve Pullman coaches over inclines of 2.2 percent. Two prototypes were finished in December 1938 and tested on the tracks of the New York Central. They were delivered to the UP in April 1939. They had a streamlined aluminum body and only one cab. Double-headed operation was possible with either both locomotives facing in the same direction or coupled back to back.

Each locomotive had two powered three-axle trucks and a leading and a trailing truck with two axles each. Steam was produced in a Babcock & Wilcox water-tube boiler that operated at 1,500 to 1,600 psi (103 to 110 bars). It was automatically controlled and fed with bunker C oil. The steam was fed into a turbine that drove two main generators which generated power for the six traction motors with a total output of 2,500 hp. After running through the turbine, the steam went into a condenser and could be used again to feed the boiler. When using the traction motors as dynamic brakes, the heat created by the resistors was used to heat the feed water. In total, the oil and water supplies were enough for a range of 500 to 700 miles.

The Union Pacific used both prototypes usually coupled together. It did not take long until they realized that they were unreliable and expensive to maintain. Although the manufacturer claimed that they could reach 125 mph or 201 km/h without any problems, there were also some occasions where one failed and the other had to take the whole load at a lower speed. They were given back to GE in June, only two months after their delivery. The New York Central was the next railroad to test them in 1941, but again no orders followed. In 1943, the Great Northern operated them in wartime freight service due to the severe locomotive shortage, but gave them back in the same year. Both were scrapped before the war ended.