Trying to figure out what size the fitting is that goes into the proportioning valve for the hard line that runs down the frame rail for the rear brakes. It appears as though the line is a standard 3/16" with double flare ends and where the rear soft line to the axle attaches I believe it is the standard 3/8" -24 fitting, but the fitting that goes into the proportioning valve is bigger. Anyone know what size fitting that is?