Ridgway Spark arrestors on D&S Locomotives

The first and only time that I went to Durango the Ridgeway-Spark Arrestors were not on any of the D&RGW locomotives. THey had the simple spark arrestors on all of the locomotives. Why the change?
Coming from my point of view the larger Spark arrestors are something that I don't agree with as far as the appearances on 478, 480,481,482. The K-series locomotives are gorgeuos, hard working machines. I hope that the 486 will be able to retain it's appearance without one.
One other Argument that I have is that the k-series locomotives never wore these devives in regular service during the days up to 1970s when they were run by the Rio Grande.