Western Pacific 501 was the Western Pacific's first diesel-electric locomotive. Sent west by the Electro Motive Corporation in 1939 to demonstrate diesel power, it was tested in various locations and services in late September, and within two months management approved buying the engine and building two sister locomotives, beginning the company's drive to replace steam locomotives. Less than 14 years later, the Western Pacific became the first large western railroad to be completely dieselized. The 501 worked at several terminals, including San Francisco, where it helped eliminate smoke and steam while spotting cars inside a can factory. Early in its career it usually worked yards and spurs in Oakland or San Francisco, including switching the barges and ferries that carried freight cars between the two cities, and in later years it was more often found in Sacramento or leased to the subsidiary Sacramento Northern. In 1965, the 501 and sister 502 were formally transferred to the Sacramento Northern, renumbered SN 401 and 402, and used to eliminate that line's last electrified freight operation between Marysville and Yuba City, California. By the late 1970s it had become a source of parts to keep other locomotives running, but in 1980 401/501 was repaired and sold to Corn Products Corporation in Stockton, California, for use as a plant switcher. In 1987, Corn Products donated the locomotive to the Feather River Rail Society, and it has since been restored to its original Western Pacific appearance.