I have a National Boiler model AO6. It began life as an oil boiler. It was in use from the 40's to the late 70's. I got it when it was replaced by a modern natural gas boiler. My goal was to convert it to hand fired coal. In the early 80's I bought and still have everything except the cast ash pit door to convert it back to hand fire. The boiler is a sectional cast iron boiler with many huge tappings. When used for coal it's rated 19 lbs/hr., 690 sq. ft. water. Any interest in it?
The company where I bought the conversion castings is long gone. The area is now part of the Johns Hopkins Hospital campus.