FIG. 4A is a fragmentary cross sectional view of a modified but conventional nozzle with water jacket cooling and shown in operative position relative to the upper and lower cavity plates of the mold assembly of FIG. 4 FIG. 5A is a cross sectional view taken on the line 5A???5A of FIG. 5B illustrating a first embodiment of a two-piece manifold plate and associated mold cavity injecting nozzle both