Who makes the best water pump for the Y? I was prepared to buy a Casco pump, but someone I know said that his Tbird actually ran hotter with the Casco pump. His conclusion was the Casco circulated the coolant too quickly, not giving it sufficient time for the radiator to cool it. He re-installed a stock pump. He has no cooling problems with stock radiator and electric puller fan. His car is air-conditioned, and he lives in the California Central Valley, where we have hot summers. He did not say if he has the smaller water pump pulley. 

I had a good experience with an Edelbrock aluminum water pump on my 5.0 Mustang. John Mummert no longer offers the Edelbrock water pump for the Y. I've read mixed reviews for Flowkooler. I want to stay away from rebuilt pumps.