Northern Pacific 5120, a Z-6, leads a westbound extra freight up Bozeman Pass west of Livingston, Montana, in May 1954. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train.

Northern Pacific 5120, a Z-6, leads a westbound extra freight up Bozeman Pass west of Livingston, Montana, in May 1954. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train.

Northern Pacific steam locomotive 5121 at Livingston, Montana, on June 08, 1955. Number 5121 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, roster photo

Northern Pacific steam locomotive 5121 at Livingston, Montana, on June 08, 1955. Number 5121 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5123 missing drive rods at Livingston, Montana, circa 1955. Number 5123 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5123 at Livingston, Montana, in September 1953. Number 5123 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5123 at Livingston, Montana, on June 07, 1955. Number 5123 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific 5124, a class Z-7, hauls a westbound extra freight out of the yard at Livingston, Montana, on May 23, 1952. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, freight train, stock car.

Northern Pacific steam locomotive 5124 at Livingston, Montana, on May 23, 1954. Number 5124 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo

Northern Pacific steam locomotive 5125 at Livingston, Montana, on June 08, 1955. Number 5125 is a class Z-7 built by Alco-Schenectady in 1941. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive in roster photo