By the time I arrived in Durango in 1981, as I recall, all 3 K-28's had knife switches for the head and back-up lights. Class and number board lights no longer existed on those locomotives.
Looking in the Durango DRGW parts room, there were many knife switches and the remains of some of the fancy Pyle switches tha Earl described. I don't think any particular locomotive or class had any specific type of switch at any given time, but what was ever available at the location at that time when a switch needed to be replaced..
Parts are parts......
MD Ramsey