Matt:
The following comes from research I did on the K36s and will probably be published by the Rio Grande Modeling & Historical Society sometime.
The D&RGW started to upgrade their lines for the K28s and K36s in 1923. The loop wye was installed at Durango in 1923.
In 1924, the Alamosa 65foot turntable was moved to Durango and replaced with an 80 foot second hand tt. Interesting note was that the D&RGW drafted an AFE for moving this turntable to Monarch, but changed their mind and moved it to Durango. The new coal chute was built in Durango at this time. In December of 1925 three inspection pits in the Durango roundhouse were extended to accomodate the 480s.
This was all part of a major upgrade of the narrow gauge main lines from Gunnison to Salida, Salida to Alamosa, and Alamosa to Durango to accomodate the 36s.
In February 1925, the new coal chute was built at Chama and a second hadn 65 foot tt installed.
At Gunnison, the K36s had to be turned on the wye and worked on outside. It was not until October 1926 that an 80 foot turntable was installed there and three stalls of the roundhouse extended ten feet. A longer turntable was installed at Marshall Pass and Sargents.
Bit of trivia, the first run of a K36 was number 480 from Salida to Sargents and return on August 26, 1825.