Dag Nabbit Fred you beat me to it.
I recently had a similar problem with my 51 1-ton, with huck brakes, due to a broken return spring. My brakes weren't completely locked, but there was considerable drag. I think Fred pegged it.
Chevy Duty sells them for $8 ea. You can probably get them at NAPA too but I bet they make you buy them for both sides for $15-18.
