Some suspension and brake questions

OMM from what I understand, there were 2 types of drum setups from 73 up.

9" SBP smooth drum which used SBJ UCA and older spindle I am assuming from 63-72

10" SBP finned drum which used LBJ UCA and special spindle made from 73-

I got one set of arms off fakebook off a truk lagoon rusty 74 slant sux duster with 10" finned SBP drums. They are BBJ

The other set of BBJs I got out of my local wrecker yard. It was also a 74 valiant slant sux with 10" finned drums.

Wheel studs on the valiant were also smaller than the 1/2" studs on the 5x4&1/2 drums. I think they were 7/16" studs