Hank,
Thank you for this. All very interesting. I note you mention 168, 169 and 172 were in the Gunnison area in the early 1930's. do you have any evidence of 169 being there other than the previously mentioned photos in Montrose? I don't doubt you-- just curious of when it was there and when it moved south to Alamosa. We know it was in Alamosa and on the Santa Fe branch in April 1933 from the Otto Perry photos. Aside from the movie work, I have not seen any evidence of a T-12 in regular service anywhere after May 1933. As to T-12's on the Pitkin branch, I doubt they would have been lighter on the rails than a C-16, having fewer drive axles. But I would like to know what the records show.
Also, as to when service stopped on the Pitkin branch, I suspect it was earlier than May 1934, when abandonment was authorized. I say that because in the Fall-Winter 1932-1933, the Fall-Winter 1933-1934 and Summer 1934 timetables, all show service discontinued on the Pitkin branch. I suppose an occasional unscheduled freight might have been venturing up the line, but likely powered by a C-16.