Others didn't even bother with a bunker; rather, the coal was just piled on left side of the cab floor.
The Glen Alden Coal Co. mine at Wanamie, PA didn't carry any coal on the locomotives. Their runs were short and they fired from piles along side the tracks, or they just took some from the coal jimmy next to the locomotive.
http://www.undergroundminers.com/oldwanamie1.htmlKeith