Proportioning Valve Kit: 64-85 GM Disc/Drum * SIDE MOUNTProportioning Valve Kit for GM USA disc brake front, with original or with the disc conversion upgrade this is the SIDE mount kit type. GM Kit for Disc Drum; For use with 3 8" Ports; Left Mount Brass Proportioning Valve, Steel Lines, Bracket and Proportioning Valve Plug. ALSO BUY A PVTOOL if you don't have one.. listed under "PVTOOL" This VERTICAL MOUNTED proportioning valve kit provides proper front to rear balance. We purposely have the # "PVTOOL"