Northern Pacific 5106, a class Z-6, leads an eastbound extra freight at Livingston, Montana, on May 23, 1952. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train.

Northern Pacific steam locomotive 5106 at Laurel, Montana, on September 04, 1953. Number 5106 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 5106 at Laurel, Montana, on September 04, 1953. Number 5106 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 5105 at Livingston, Montana, on August 23, 1943. Number 5105 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific 5105, a class Z-6, leads a westbound extra freight out of the yard at Laurel, Montana, on August 17, 1949. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train, freight yard.

Northern Pacific 5105 and 5108, both class Z-6s, lead a westbound extra freight at Glendive, Montana, on September 03, 1953. It was unusual to doublehead the big Zs due to the loading of bridges. This configuration was likely to transfer power to another terminal. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train.

Northern Pacific steam locomotive 5105 at Glendive, Montana, on September 03, 1953. Number 5105 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific 5105 and 5108, both class Z-6s, lead a westbound extra freight at Glendive, Montana, on September 03, 1953. It was unusual to doublehead the big Zs due to the loading of bridges. This configuration was likely to transfer power to another terminal. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train.

Northern Pacific steam locomotive 5105 at Glendive, Montana, on September 03, 1953. Number 5105 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 5104 at Missoula, Montana, on August 19, 1943. Number 5104 is a class Z-6 built by Alco-Schenectady in 1936. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo