Here we have a factory original Kelsey-Hayes used Proportioning Valve for a 1965-66 Shelby GT 350, Mustang GT or 66- 67 Thunderbird. A critical part of the Disc Brake package, the Disc proportioning valve balances the hydraulic pressure between the front and rear brakes to equalize the correct ratio of braking for optimum stopping power the controller for braking balance. This item has been disassembled cleaned and inspected by one of our experienced classic repair technicians at Mustang Masters. This is a moderately pitted up unit and it is a perfect candidate for that driven cars, we believe this prop valve will be serve most, if not all owners.Given the power and speeds that these high-performance cars are capable of, a factory correct brake assembly is just as important as a finely tuned engine. Ford engineers designed this unit specifically for these cars, and while aftermarket units may offer similar functionality, none come close to the quality and performance of the original!We often offer a complete selection of power disc brake changeovers, and if you've watched our auctions last month you've seen us offer 65-67 Mustang GT or Fairlane GT Kelsey-Hayes 4 piston brake changeovers, also 68-69 Disc for a Mustang, Torino, or Cougar, and finally the 70-73 Mustang or Cougar, which is an excellent replacement for those who are entertaining installing those improperly designed Granada changeovers offered at a discount price.Be sure to check our new improved website MustangMasters.com, our other eBay stores MustangMastersPlus and MustangMastersNOS65to73 and our other auctions on MustangMasters428, as we offer a new selection of rare, hard to find, and desirable parts on eBay each week. Like us on Facebook and follow us on Twitter at MustangMasters.Another fine part from your friends atMustang Masters.For more info, please call 904.724.3927 or view ourAbout Mepage.Thanks!Freddy.