 The two locomotives were delivered to UP in April 1939, and they completed test runs and participated in a variety of publicity events for the railroad, including the grand opening of the Los Angeles Union Passenger Terminal, the world premier of Cecil B. DeMille's film Union Pacific, and even an inspection by President Franklin D. Roosevelt. While the locomotives displayed excellent acceleration and an ability to maintain schedules better than conventional steam locomotives, they also demonstrated serious reliability problems and relatively high maintenance costs; they never entered regular revenue service.
