I have come to my own conclusion that the Narrow Gauge K-27's and the Standard Gauge C-41's were the D&RG's science projects, many changes on these locomotives were made at the hands of the Burnham/Alamosa Shops through the tenure of service for their Railroad. Both and most of them received Piston Valve changing over from Simple slide, of course the K-27s were delivered with their Compound design, but modifications were in their future.
Looking at 1022 and how she acquired a Vanderbuilt tender of the few pictures that I found on Nathans site 1002, 1012, 1015, 1028 kept the Stephenson Valve Gear, where 1013 and 1022 received Wahlscherts Valve Gear. Even better yet, 955 was converted to a Tank engine in 1937, #01 still in her Simple Slide, You've got to like that fabricated tank, they must have looked at the drawings of the 50 and 51 on the Uintah railway, positioning the tanks in the most central area of the Locomotive to keep the locomotive evenly balanced with the weight of the coal box on the back. She looks like an odd duck in some ways, but the Burnham Shops did a great job.
Still a Student,
Dave