[Gearhead999]

The proportioning valve has shifted over and shut off the rear brakes.

Fine the valve. Left apron, under the mastercyl. Pull the electric switch out of the center. [It's the part with a wire] Put a sharp, pointed, instrument down there and move the valve to the center. Hold the valve there and bleed the brakes.

KD and other companies use to make a tool that you could screw in there to hold the valve. I don't know if you can find it anymore. Anyway, if you can't.....fabricate something to hold the valve and bleed the brakes.

Just a typical old car.