I believe that an RPO was used between Gunnison and Montrose till the passenger train service was pulled between these points-- I believe in 1936. Interesting to note that the D&RGW retained the mail contract between Gunnison and Montrose, even after the train service only went as far as Gunnison from Salida. Reportedly, bags of mail were just put on a truck between Gunnison and Montrose as the RPO was turned around in Gunnison and sent back to Salida on the Shavano. So, during the Shavano period (March 1937 to November 1940), the postmark for mail cancelled on the Shavano RPO was still "Salida & Montrose".