Right you are, Jason, this was taken immediately prior to the Rocky Mountain Railroad Club Excursion in May of 1949.
The engine had already made a trip over the line to Durango. One indident that took place on that run was that the the Engineer broke out the C&S two pane cab windows with a brake club between Delores and Durango, because they were stuck.
In this photo, the RGS has replaced the windows with their usual 4 pane style. Also note the inward opening cab doors on the front of the cab, still C&S style.