There has been a book written on this subject but it is great to see and pick the trains in the movies.
One recent extremely hot day here in Australia kept me indoors (like being snowed in in the US?), so I had a slack day and watched a couple (or three) of John Wayne westerns.
McClintock and Rio Lobo, the trains were different and standard gauge and I couldn't pick them, but I did note they reused movie sets with the bridge over the creek and warehouse being used in both movies (shoot out in Rio Lobo), and the depot in McClintock looked like the same one in Spencer Traceys 'Bad Day at Black Rock'.
Wayne from hot Oz