Frank: The ECI hot rod brakes folks show a dual remote booster in their catalog that looks like a real good candidate for replacing the stock hydravac unit which would only boost one side of a split system. This is something I have on the back burner for my '48 2-ton GMC. My plan was to replace my single shot master with a dually and then go to a dually booster. The master now on the truck would be a good candidate for sleeving it's been honed to the limit!!!