This is the GM Proportional Valve used on all GM cars and trucks from 64-81. has the plastic switch that is in the top of the Prop. Your brake warning light lead plugs in and if there is a loss of pressure a warning light in the will be on. This is exact to NOS in every way even featuring the correct finish and design. Please my exclusive Inline Tube e-bay items. These are the details that separate the first place cars from the rest.