After ordering my rebuild kit for my the engine in my 74 Corolla, I have had some troubles locating a suitable oil pump. The place I ordered my kit from, as well as Auto Zone, show there being a difference between oil pumps made in July 74 and those made before that date. Can anyone confirm that? The reason I ask, Auto Zone does not carry the pre-July '74 pumps, but they do carry those made after that date as well as the '73 pump. Surely early '74 pumps are not some sort of weird transition part? Even if they are, would I have any issues fitting one of the other two pumps?