To continue the update to this old thread:
The D&RG bought new 4 different classes of 4-4-0's.
Class 37 were 8-16C's (11x16 cylinders) with straight boilers. All three were painted lake and gold and carried extensive brass trim and natural wood finish cabs.
Class 38 was classed as 8-18C, but was essentially an 8-16C with increased cylinders (12x16) and a couple other minor differences. Dimensions and weights were otherwise unchanged from the 8-16C. All six had wagon top boilers. The first of them (Rio Bravo) was lake and gold with a lot of brass and wood finish cab. The next pair were olive green, still with brass trim and wood finish cabs. The final three were green & color with plain decoration, less brass, and painted cabs.
Class 42 were the most numerous class of 4-4-0's the D&RG bought, 12 total, 8-18.5C drawing 2. These were basically similar in size and weight to "Eureka", differing mainly in having taller drivers (all the D&RG 4-4-0's had 45 inch drivers) and a longer cylinder stroke (12x18). The boiler internals were a bit different too, with a larger number of smaller-diameter tubes, plus a few other odds and ends different (different tender, etc). Nine of them were painted olive green. The final three were black.
The last 4-4-0's the D&RG bought new were class 42.5, still 8-18.5C's with the same 12x18 cylinders as the previous class, but with straight boilers and long shallow fireboxes (I think they planned to burn Utah anthracite?). They were ungainly looking, rather ugly machines. All three were black.