10” rear drum questions

There was a bit of a panic a few years ago when 10 x 1-3/4 rear drums were momentarily out of production, due to a mix-up of superseded part numbers or something (you have probably noticed that many source's brake part listings for A-bodies are sketchy in several respects). But they are out there now, just some web listings haven't caught up yet. If you don't see them for your year and model, try another year or model with the same equipment: any Dodge or Plymouth A-body 1967-72 with a V8.