My 1957 Accessory Installation Manual doesn't show a Hydrovac for the trucks, only the cars. But it is shown in the 1958 Accessory Installation Manual. It's shown hanging on the right side frame rail over the front axle, with (2) hydraulic lines running from it back to the crossmember that has the right front brake line already on it and then back up to the MC. The Vacuum hose comes from the intake manifold and crosses over the top of the engine between the front of the valve cover and the T-stat housing.
Mike B
