Doghouse Removal on the "Silverton"

Ed, it was the D&RGW which did away with doghouses on the K-28's in 1964.
It was done to keep the head end brakemen in the train and not whiling away his time in the relative comfort and isolation afforded by the doghouse.
I imagine the doghouses on the 480's were removed by the D&S for two reasons. First, to restore the engines more to their original appearance, which is consistant with other changes the D&S made on the 470's. Secondly, they were in rapidly deteriorating condition, and would have required money to restore.
A third reason, of course, would have been the same as the D&RGW's logic in 1964. To keep the head end brakeman in the train.