SP&S 4-6-6-4 steam locomotive Number 905, Class Z-6, taking on water at the Northern Pacific Parkwater shops at Spokane, Washington in August 1955.

SP&S 4-6-6-4 steam locomotive Number 905, Class Z-6, at the Northern Pacific Parkwater shops at Spokane, Washington in August 1955.

SP&S 4-6-6-4 steam locomotive Number 905, Class Z-6, at the Great Northern servicing facilities at Hillyard in Spokane, Washington on April 18, 1948.

SP&S 4-6-6-4 steam locomotive Number 905, Class Z-6, at the Great Northern servicing facilities at Hillyard in Spokane, Washington on April 18, 1948.

SP&S 4-6-6-4 steam locomotive Number 905, Class Z-6, with a 96 car eastbound freight arrives at Pasco, Washington on June 1, 1941. Photo by Al Farrow.

SP&S 4-6-6-4 steam locomotive Number 904, Class Z-6, with another Z-6 in storage at Vancouver, Washington.

SP&S 4-6-6-4 steam locomotive Number 904, Class Z-6, in storage at Vancouver, Washington in October 1956.

SP&S 4-6-6-4 steam locomotive Number 904, Class Z-6, at Vancouver, Washington in August 1953. Photo by Stan Styles.

SP&S 4-6-6-4 steam locomotive Number 904, Class Z-6, at Vancouver, Washington in April 1953. Photo by Stan Styles.

A crew member poses in front of SP&S 4-6-6-4 steam locomotive Number 904, Class Z-6, at an unknown location and date.