When 20 years had passed since the later class K-27 was purchased from Baldwin, the D&RG purchased ten additional locomotives from ALCO-Schenectady. These were also Mikados with an outside frame, in which the cylinders, driving and coupling rods, as well as the valve gear were located on the outside. They were initially listed as class 140 and were renamed into the now better-known class K-28 after the D&RGW was founded.

They were the first D&RG locomotives to have a superheater from the beginning. The fact that the class designation indicates only a slightly higher tractive power compared to the K-27 is due to the fact that the drivers now measured 44 instead of 40 inches. However, this, combined with better mass balancing, ensured higher speeds, which is why the crews nicknamed them the “Sports Models”.

During World War II, seven were drafted by the military and taken to Alaska, where they served on the White Pass & Yukon. These were scrapped after the war, while the other three remained in use with the D&RGW until the fifties. They then came to the Durango & Silverton, where they have been pulling tourist trains ever since. The 473 is still in use today, having been converted to oil firing in 2022.