I'm searching for a brake proportioning valve for my 82 K20 Burb. It is leaking bad even just when sitting there which constantly drains the rear drum reservoir in the master cylinder. A C Delco made one (part number 172-1353) but no one sells them anymore. LMC Truck wants $99.95 plus shipping. There has to be a better option out there.
Are you telling me that there isn't one available at NAPA, Checker/Schuck's/Kragen, O'Reiley's, Autozone, CarQuest? I'm a NAPA kinda guy myself now. My dad needed a brake booster and master cylinder for our '76, NAPA had NEW units, not rebuilds, for the price of one of the items from the dealership.
Oh, did you try www.ChevyDuty.com ? I would definately not go pull one out of a junkyard, too many unknowns.