My first thought was that this was a stock extra. However the first 10-11 cars appear to be regular box cars, followed by a bunch of stock cars then some more box cars near the rear. Being a stock extra would also perhaps be the reason for 3 engines, which may have added the extra box cars so they got their monies worth out of the third engine...Just a guess.
However, I do want to point out one thing to the younger ones on the list. This was the proper way you would see three-engine trains on Cumbres pass,
although they were not that common. It would generally always be one engine on the front and one pusher, or one midtrain(less likely). But when I third engine was needed it would go up front, meaning a stop at Lobato Trestle. At Cumbres two helpers would likely go back to Chama.
Nice photo and the way I first saw Windy Point before the road was rerouted.
Greg