Abstract: A stuffing box as applied to the sliding joint between the piston (ram) and cylinder of a hydraulic ram assembly in a hydraulic injection molding machine has a packing retainer assembly with a retainer ring with a protruding gland that extends into the stuffing box thereby to act as a pilot means to insure concentricity between the stuffing box, gland, and ram. In addition, the inside diameter of the gland has a support bushing groove in which is mounted a support bushing that has an inside diameter less than the inside diameter of the gland and which is fitted in sliding bearing relationship to the outside diameter of the ram and held there by the gland. The support bushing is preferably manufactured in two pieces from a fiber reinforced low friction resin selected from the class consisting of thermosetting resin and thermoplastic resin more preferably phenol formaldehyde and polytetrafluoroethylene.