Some great information provided by the always insightful Jerry Day
The entire line from Salida to Gunnison, Salida to Alamosa, Alamosa to Durango had to be rebuilt for the K-36s. The Marshall Pass line did not require as much work as the Cumbres Line as the K-27s and K-28s were first used there. The Crested Butte branch was rebuilt in 1910 and 11 to handle the K-27s. Ballast work was done in spots where there was water problems....at the bottom of hills, etc. All this work took years, some of it was started in the early 20s in anticipation of the K-28s and possibly 2-8-8-2 engines. Following are some examples of work being done...
August 1925
Durango
Roadway forces have almost completed laying side tracks and wyes with 65 pound rail in anticipation of the heavy engines. Bridge forces have also strengthened the bridges over the division. The Jordan Spreader has been doing a lot of good work between Pagosa Junction and Durango clearing out cuts and widening fills. T.P. Hunt says he thinks it is a great machine.
September 1925
Salida
A small gang of 25 men is engaged on the Alamosa branch and have laid about 7 miles of second hand 52 pound rail between Villa Grove and Alamosa, replacing 30 and 35 pound rail. This is in order to accommodate the new power which is expected to arrive this month. The work of strengthening bridges between Salida and Marshall Pass is well underway and we are ready to receive the new narrow gauge engines. We have a narrow gauge ditcher working in the vicinity of Marshall Pass and have just completed an AFE covering the same in this vicinity. We have a small B&B gang on the standard gauge main line and on the narrow gauge mainline repairing stock yards and painting buildings.
Chama
Now that the steam shovel and ditcher are busy on Cumbres Pass, the roadbed will soon be placed in first class condition for the fall stock rush.