Anthracite coal, was still use in many an SP caboose, including the cupola cabooses, used on locals into the mid seventies.

We had a caboose stove, that a previous roomie had installed in one of the "hippie" hoghead pads up in Echo Park (used to take the old "back way"-LA's last "dirt" road, down to Stadium Way, to get to Taylor, before it was closed due, after too many bodies from the "hillside" strangler).

We used to get some coal from the cab track by the hump and fire that sucker up. Once, we put a small piece of "coke" that I'd picked up on the lead, into the caboose stove, and almost melted the thing. It's a good thing it was only a small piece.

I had a conductor who made the mistake of making me shove his caboose first, with the coal stove smoke blowing in my face down, at Anaheim one cold night. I made sufficient use of independent only "train handling" techniques to ensure he didn't do that with me ever again.