David,
Thanks again for the thoroughness of your post on the various drill bits.
In return for that, I have this from my friend Mac who says about your question of class vs. marker lights for the PRR B6 switcher classes:
Classification lights were boiler mounted ,as it denoted class of train and whether it had the right of way. As switchers didn’t get priority they normally had marker lights only. Originally mounted only on the pilot or tender these normally showed as red as it was seldom doing more than switching various industries or handling locals. They were Pyle national markers. However, during the 40’s pilot mounted markers were often replaced with boiler mounts which were smaller almost can like mounted on a bracket above the handrails smoke box side below the stack and generator. ---Mac
Tom
