476

Sadly, the K-28 which is no longer servicable is 476, which was for many years regarded as the "favorite" of the three survivors of this class.
The problem, as I recall, is that the cylinders have worked themselves to where they are no longer stable and secure in the frame. To fix this problem will require complete disassembly of the locomotive to be able to get to where the problem can be reached. The age and condition of the boiler will probably make it feasable to be considered for replacement at that time, given the serious nature of the kind of rebuild which will be necessary to return this veteran to service.
sda is correct, I believe El Coke remains as the only engineer to have "worked" all four classes.
Separate from the running charactaristics of these engines, the K-28's were built and used for both passenger and freight service. Seven of the ten locomotives built for the D&RGW were shipped to Alaska during WWII and never returned. All 7 were scrapped. They are the only K class engines built by Alco (the others are Baldwin).
The three K-28's were the workhorses of the "Silverton" train for all the years under D&RGW ownership and they were worked like dogs for years and performed with excellence. The 473 and 478 are now the only engines owned by the D&RGW/D&S/C&TS which have been in continuous service since they were built, except for minor servicing and repairs. All others were either set aside or retired.
These engines have always been my favorites, and I hope to be able to see 476 returned to service again one day, but it will be very expensive and a long time off.
At least 476 can be seen in the Durango museum at the roundhouse. I'd like to see her painted in Rio Grande livery, with her "fake" diamond stack again. I know this would not be popular with a lot of folks, but it's how she looked for more years in service than any other configuration. Besides, I liked the way they looked. Lots of great memories for me and thousands of others.
Mike