Thanks for the insights. These are the kinds of things that make the Rio Grande Southern such a fascinating study.
OBTW, interesting too is the tender water capacity of 3,000 gallons. The Porter tank was dismantled and shipped to Ridgway when the tank there burned in the early years. This made the haul out of Durango to first water at Hesperus a seventeen mile trek. The C-class engines have 2,500 gallon tanks and were frequently found running lite for water with their train parked on the Mule Shoe. This may be one of the reasons why the T-19's tended to be kept on the South end.