I need a little help/advice

Yellowdartdave,
I do not believe that is entirely correct. I have a 1973 swinger that came with a slant six and it had disc brakes standard. I believe drum brakes stopped being offered after 1972 (on a-body front ends anyways. I know they stuck with drums on the rear.)

If he has a small-bolt pattern on the reaar, then it sounds like somebody changed out the rear end at some point.

Please feel free to correct me if I am wrong, everybody. I'm still learning.