All of the cars so far have disc brake master cylinders. You can tell because they have a big reservoir and a small reservoir. The drum masters will have equal size reservoirs.
JeffC,
That's what I thought as well, but here's a 1971 Duster parts car in my backyard, I can't swear that it's correct but it looks like original parts and it runs, drives, stops normally, it is a power drum brake car but since the fender tag is not coded for power brakes I can only assume the booster was added.
