Originals with fangs and square bolt hole openings were used through 70 GT350 production and available as over-the-counter / service parts until at least the mid 70's. Sometime after that the area surrounding the PCV and breather openings were machined slightly larger in diameter and the fangs disappeared. Then the rounded hole openings became available from Ford which I believe was the first version reproduced, I'm sure others will have more info on this. Now you can get repros with square openings and fangs, but they do have different baffles than originals.
Dave