Would like to know why when I look for brake drums for a 1969 chevy C10 stepside short box everyone is selling?

the same drums for the front and back (6 lug) (15 inch)but on my truck the front drums are attached to (a spindal which is held on by a bearing,nut and cotter pin)..is this original or could they be off a suburban,jimmy etc..just seems weird that every book I look into they sell the same drums for back and front