Help ID this brake drum - possibly 30's or 40's Buick

[sleeve-valve]

This brake drum was on a rear wheel of my 1939 Buick Special but it is not correct for it. It is for 12 inch x 1 3/4 inch shoes like the 39 Special but the end that goes inwards towards the car has a different flange (see photo). It would only work on the 39 Special with a spacer between the drum and the axle else the drum would rub against the backing plate. The bolt holes and the 2 piece construction are the same as the 39 Special, the only difference being the shape of that flange on the inward side. What is it from?