My "DUH" Moment.
 

I've been working on the brakes on my 1970 C10. I was going to switch to disk on the front but doctor bills and a new AC unit for the house put that on hold. I decided to just rebuild the drum brakes for now.
One of the shoes on the drivers front was dragging on the inside of the drum. I took the drum off and didn't see anything wrong so I adjusted the shoes and replaced the drum. Still dragging. I took it back off and see where the corner of the shoe had wear where it was dragging. Tried a different drum, still dragging. Not seeing anything out of place I grabbed a big ol' file and filed the corner of the shoe down and reassembled everything. Better but still dragging so I took it apart and filed some more. This time success no more dragging.
I was talking to my cousin and I said something has to be bent or out of place. After going through a list of possible causes he mentions the backing plate. DUH! it has to be the backing plate. All I needed to do was to give the backing plate a couple good whacks in that spot. I spent two evenings taking the brakes apart reassembling everything and finally filling on a perfectly good brake shoe.