It's one of my favorites, too. Which is why I devoted lots of space to it in my book. I never could establish why #476 was selected for use in the films made in the 1950s, after the C-class locos and K-27s were gone. While #478 did appear as a background loco in
Night Passage, it and #473 weren't used much until later in the 1960s. Number 476's stardom was probably just a coincidence, but could have been because it was the favorite loco or someone at the railroad ("give 'em the 476"), or filmmakers liked the number ("we'll take the spirited 476"). I encountered lots of questions that may have been answerable decades ago but the right people are long gone now. Yes, watch the film again. It always prompts me to pull a few Rio Grande books off the shelf and revisit them.