Abstract: A swing clamp apparatus adapted to be mounted adjacent a work surface includes a housing provided with a bore defining a longitudinal axis, and a piston received within the bore and being movable in the direction of the longitudinal axis. A clamping arm is supported on the piston for movement therewith between a clamping position and a releasing position. A first passageway is provided for delivering hydraulic fluid from a source of pressurized fluid to the first bore section of the housing to move the piston in a first direction and additional structure shifts the piston in a second direction opposite the first direction. The passageway includes a plurality of external ports formed in the housing and a manifold with which the plurality of ports communicate to permit fluid to be delivered to the first passageway, and a number of plugs are used for plugging any of the plurality of ports not used during delivery of fluid to the passageway in order to prevent leakage of fluid from the manifold.