Atlas N: Chicago & North Western #1619 RSD4/5 Locomotive

From 1950 to 1956, ALCO offered a six-axle road-switcher which was more commonly found in the west. The RSD-4/5 was externally very similar to the RS-3, having six-axle trucks as an obvious spotting feature. They produced the same 1,600hp as an RS-3, but offered increased tractive effort due to the use of a larger generator. Many RSD-4/5s were assigned to operate in mountainous territory (with varying degrees of success) on the Southern Pacific, Santa Fe and the Utah Railway.