Josh:
A complete list of movies filmed on the D&RG (and other RR’s) can be found in Larry Jensen’s (no relation) “The Movie Railroads”.
Another reference book you should consult is the Colorado Rail Annual for 1963 contained in the Collected Colorado Rail Annual book by the CRRM. One of the key factors in reshaping Durango for tourism was the 1962 decision by the ICC to reject the Rio Grande’s application to abandon the Silverton branch. This forced the RR to rethink its policy and they brought in Alexis McKinney to spearhead the development of the Silverton and the area around the station in what became known as Rio Grande-land. You should probably talk to Bob Richardson and Amos Cordova as I am sure they will likely have first hand information on what you are seeking.
Rod Jensen