A dual Master could be used. Just put check valves in the discharge of each reservoir, then go to a common header to the Hydrovac. You would have a single hydraulic signal going to the hydroboost. If you lost 1 reservoir, the check valve would prevent backflow into that side. The chance of loosing one side with a short line, no rubber hose would be nill. You'd still lose all breaks except parking brake if the hydrovac or downstream lines were lost. If me, I'd replace, repair the hydravac and old master. Good luck. Jim
