Water pump OEM Toyota or GRAF

all graf water pumps with metal impellers are tested and balanced before packaged so why would there be any reason not to buy them ?

Just following up on this- I replaced the water pump and that appears to have resolved the issue. I have been monitoring it frequently and there has definitely been no sign of coolant leaking under the car in the area it was doing it from.

Further, the metal unit (Graf) had a sort of reptile-skin texture to the impeller fins, no doubt a product of the casting process. I spent some time with a dremel polishing the fins (because that's how I roll ) to get them as smooth as the plastic ones being replaced.

I went with the Graf in my 95 passat glx. The graf has a cast iron impeller wheel. The stock one that was in there was plastic and some fins broke off when the pump failed