[kipps]

The proportioning valve is located directly below the radiator on a crossmember. It's easiest to access from the bottom of the truck. There is no button to press. Supposedly, a plug can be removed, and a special tool installed to re-center the prop valve. This is pretty rare. Most all brake jobs can be done without worrying about that valve at all.

Definitely replace the rubber hoses. An internally collapsed hose will give the same symptoms as a sticking caliper.

I don't know much about fluid flushes. Whenever I've been messing with brakes, I'm just focused on getting rolling again. I don't want to screw around with any preventative maintenance at the same time.

I don't mind reman parts. The price is right, after all!