SBP 10" rear brake drums and shoes

I just looked and rock's are $68 ea, which is hardly a clearance price. But I have seen people ask $80 for used drums on ebay.

For some reason, they don't list them for my 65 Dart, which I recall is also 10"x1.75" rear. I got a set of front drums cheap at rock ~$20, thinking they were for rear but their listing was wrong. It looks like if I could cut off the single lip, they would fit my rears, but maybe there is something different about rear drums I miss. I have some that have double-lips that envelope over the backing plate edge. That must be the Canadian "keep out snow" design.