Abstract: A multi-station injection blow molding apparatus for producing hollow plastic articles, including vertically stacked preform injection molds at a first station, vertically stacked blow molds at a second station and an indexing head assembly having upper and lower core bearing indexing heads which are rotatable in a horizontal plane when the molds are open and also are movable vertically relative to and in correspondence with movement of the molds during opening and closing of the molds. In one embodiment, the movable supports which support the mating mold portions of the upper and lower injection and blow molds are coupled to the mold clamping mechanism of the apparatus through mechanical linkage which causes the upper and lower molds to be opened and closed simultaneously. In another embodiment, the movable supports are coupled together, causing the upper and lower molds to be opened and closed sequentially.