The cab unit was former UP PA1 607 built in January 1947 (c/n 76311), retired in March 1961. It was rebuilt, retaining its Model 244-16 prime mover, adding 2,000 horsepower to the locomotive consist. The B-unit was former Great Northern Railway class W-1 electric locomotive built by GE in June 1947 (c/n 28448), retired by the GN in August 1956, sold to the UP as scrap in 1959. Between 1959 and 1962, the UP designed and built a coal-fired turbine, using a modified turbine power plant from a retired 50-75 series turbine locomotive, producing 5,000 horsepower. The coal tender was from Challenger (4-6-6-4) 3990. The completed 7,000 horsepower locomotive entered service in October 1962, and tested until May 1964, making its last run on May 12. It was deemed a failure, due to turbine blade erosion and soot build-up caused by the coal fuel. It ran less than 10,000 miles before being struck from the roster on March 15, 1968. The cab unit was traded to GE, the B-unit and tender were scrapped by the UP at Omaha.