Shame they always have to have a modern helper attached, kinda spoils the look.
Back in 1984, when they ran the SP Daylight to the New Orleans Worlds Fair, they had Daylight painted diesels for helpers through the mountains, but uncoupled them and just ran the steamer for the low-gradient segments. Between Mojave, California, and Palmdale, California, 4449 was running solo with her passenger cars, and showing what she could do on the long straightaway. Made for some excellent photo opportunities. After watching her travel through the Tehachapi Loop, I looked into, and got a ticket to ride the train on the return trip between Phoenix and Yuma.
A few years later, both she and UP 844 traveled to Los Angeles for the anniversary of the LA Union Passenger Terminal. On their outbound journeys, the two steam trains "raced" up Cajon Pass on their separate rail lines, neither train augmented with diesel helpers. When I learned they were going to do that, I told my boss I was leaving work early so I could watch the spectacle. It was an impressive sight.