I tried to do some rubbings of the casting mark and I think I see F1210 or FA210
looking at the picture. under flash it looks more like FA210. That didnt show to the naked eye. The F is the lightest letter and may just be a interesting rust formation.
If you think it looks like something completely different than what im seeing I appreciate that view as well.
does the 0 at the end mean 1940?