Borrowed off another site's posting:
https://youtu.be/Oi3rXlXdMI0
https://youtu.be/-FJ34dLeZaQ
Combine/caboose 401 has the rebuilt roof and is on freight car trucks so that makes it fairly late. #9 has lost its original steam dome but still has its old headlights. Episodes show as being released in early 1954, so likely filmed in 1953?
Depot scenes are Keeler, transfer trestle is at Owenyo. Looks like filmed at south end of Owens Valley. Engines were still based out of Keeler until diesel arrived, then moved to Owenyo. Film crews were primarily based out of Lone Pine. The scenes with the rounded rocks were in the Alabama Hills on the WEST side of the valley in the Sierra foothills, while the SPng primarily ran closer to the center or east side of the valley along the foothills of the Inyo Mountains.