Colorado & Southern RailwayRocky Mountain Railroad Club Excursion - Denver to Longmont - October 25, 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954 Engine 646 - October 1954