Used proportioning valve for the 1967-68 Mercury Cougar or Ford Mustang. This is a cylindrical shaped brass valve, some times called the pressure control valve, brake valve or 'cigar' valve. For 1967 Cougars, this valve is most often found at the junction of the high pressure hose back at the rear end. 1968 had it connected to the distribution block on the driver side firewall. Will come with the C7OE-... stamped valve. Starting in 1969 the valves had a C9OE... Ford part number. These are used and will need rebuilding. Some may have tool marks from pipe wrenches or channel lock pliers from previous removal. Other valves will not, but they will have the old steel lines still attached.
Ford part # C7OZ-2B091-B.
Check out this video