Brake drum identification

[ho70]

I am still problem solving my rear brakes. I had drums and they did not fit. Got a second set (same part number) and one was the same as the ones I took off (old ones) and it fit great. It is the drum on the right. It is the same width, but a quarter inch taller. Supplier is looking for another one. Is this drum off a truck with the extra leaf spring or a 12" rear end? The part numbers are the same, but depth is different. I have a 72 12" rear with coils and the extra leaf spring. It is a half ton LWB. thanks. Service manual was no help.