There is one other aspect to this. By 1963 traffic patterns had changed dramatically compared to a year or two earlier. Traffic was getting light, and it was frequently necessary to run a flanger in advance of a normal freight move because enough time had elapsed that the tracks needed to be cleared. With more frequent traffic the passage of trains would keep the tracks clear. My shots posted here represent the next to last winter they operated over Cumbres. After 1963/64 they ran no trains once the drifts got too deep.
Tom Gildersleeve