Western Pacific 1501-1503 were delivered to WP in May 1973, in WP’s dark green with orange lettering paint scheme. Of the 808 SW1500s completed by EMD between July 1966 and January 1974, these three units represented less than ½ of 1 percent, and Western Pacific was just one of 58 customers. The three units were repainted to UP yellow and gray, retaining their former WP numbers, in April and May 1984. These three SW1500s were generally assigned to the Oakland yard prior to the merger (one was used in San Francisco until WP ended its ferry service to that city), and after being repainted at North Platte in 1984, they were returned to Oakland for service. In 1987 and 1988, in a move to place all of the road’s switchers in the 1200 and 1300 series, the three ex-WP units were renumbered 1315-1317. UP 1501 became UP 1315 in November 1988; UP 1502 became UP 1316 in May 1988, and in August 1987, UP 1503 became UP 1317. These three units were formally purchased by Union Pacific on January 3, 1989 after the original lease to WP expired on January 1, 1989, and would be renumbered yet again, this time to Y1041, Y1042, and Y1043. After purchase all three ex-WP SW1500s were reassigned from their California locations to new assignments at Centennial Yard in Fort Worth, Texas. All have now been retired with the Y1043 (1503) being donated to the Feather River Rail Society in Portola, California.