I picked this guy up at O Scale West earlier this year:


I saw it sitting on one of the sales tables but didn't recognize it as something I had seen before. It was a heavy old car in nice enough shape, but the asking price was a bit high and I wasn't sure I wanted to haul it home, so I passed on it. Sometime later Charlie Morrill caught up with me and asked me if I had seen that "cool old tank car". So I went back to look at it with Charlie, thinking he was interested. The more we looked at it the more appealing it became, but to my surprise Charlie wasn't interested -- but he was pretty sure I needed to be. Well, he was correct, and I managed to talk the seller down to a reasonable amount ($20 I think).
Here's the underside:

I have exhausted all my catalogs and I still don't know what it is. The tank is a metal tube and the end frames are cast bronze. Walthers used cast bronze on their very early freight car frames and offered a metal tank option in at least one catalog (1936), but I don't have any other evidence to match this one with any certainty to an early Walthers.
At any rate, Charlie was right: Cool old tank car.
Thanks, Charlie!
Jim