Not all are created equal...some of the plates only have 4 holes, some have 6...8 is better, drill and chamfer a few more, less restrictive and aids drainback.
The center studs vary also, the ones with the hex on the outer edge and a wide open center flow the best...if you go junkyarding, check heavy trucks as your best bet. Should be able to come up with one in the yards out there.
happy hunting.
Alan627b