Cheap & easy Power Drums? '66 Signet

Darned if I know. According to the seller, it fits every Mopar ever made from 1905 to 2016 and then some, drum disc, or ???

Now we all know THAT cannot be quite true. The master DOES appear to have "equal" front/ rear sections, which would lean towards a drum master. The difference mainly is that disc masters generally have no residual valves for the disc brakes, drum masters do in both sections. Some guys claim that "modern return springs" don't need them, but I'm not sure I agree.