Burlington Northern 5617, the former Northern Pacific 2517 parked near the sanding tower at the diesel shop in Denver, Colorado, in November 1970. General Electric built NP 2517, a type U25C in 1964. Photo by GJ Werkema. Other subject classes: diesel locomotive, , U25C

Burlington Northern 5617, the former Northern Pacific 2517 parked near the sanding tower at the diesel shop in Denver, Colorado, in November 1970. General Electric built NP 2517, a type U25C in 1964. Photo by GJ Werkema. Other subject classes: diesel locomotive, , U25C

Burlington Northern 5619, the former Northern Pacific 3304 parked on the ready track at the diesel shop in Denver, Colorado, on November 1970. General Electric built NP 3304, a type U33C in 1969. Photo by GJ Werkema. Other subject classes: diesel locomotive, U33C

Burlington Northern 5619, the former Northern Pacific 3304 parked on the ready track at the diesel shop in Denver, Colorado, on November 1970. General Electric built NP 3304, a type U33C in 1969. Photo by GJ Werkema. Other subject classes: diesel locomotive, U33C

Burlington Northern 6404, former Northern Pacific 3604 at the diesel shop in Denver, Colorado, on May 24, 1972. Photo by GJ Werkema. Other subject classes: diesel locomotive, SD45

Burlington Northern 6412, former Northern Pacific 3612 at the diesel shop in Denver, Colorado, in July 5, 1971. Northern Pacific 3612, a type SD45 built by General Motors Electromotive Division in 1967. Photo by GJ Werkema. Other subject classes: diesel locomotive, SD45

Burlington Northern 6421, former Northern Pacific 3621 at the diesel shop in Denver, Colorado, on May 24, 1972. Northern Pacific 3621, a type SD45 built by General Motors Electromotive Division in 1968. Photo by GJ Werkema. Other subject classes: diesel locomotive, SD45

Burlington Northern 825, former Northern Pacific 7006B at the roundhouse in Denver, Colorado, on September 17, 1973. Northern Pacific 7006B, a type F9B built by General Motors Electromotive Division in 1955. Photo by GJ Werkema. Other subject classes: diesel locomotive, F9B

Burlington Northern 825, former Northern Pacific 7006B at the roundhouse in Denver, Colorado, on September 17, 1973. Northern Pacific 7006B, a type F9B built by General Motors Electromotive Division in 1955. Photo by GJ Werkema. Other subject classes: diesel locomotive, F9B