Are you refering to the recirculation port? The one on the right side of the engine. Some aftermarket pumps do not have the recirc port drilled but it doesn't seem to cause a problem. What I noticed in 40,000 miles with a wiend (sp)pump was that the temperature gauge would fluctuate as the thermostat opened and closed. Other than that there was never any problem other than at RPM above 5,000 it tended to blow out the gasket. Solved that problem by going to a modified windsor pump with a back plate.
Good luck,
Forest
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