It is a half inch smaller , but n one way it's good and one way it's bad , yes it helps cooling in stop and go driving , bad it wears out the belt faster , and wears out very fast when your on the hwy a lot , If the belt breaks then you have a very short time to catch it and you crack the heads , I did
it before one time , ford saw this and fixed it by adding extra pulleys for more belts to drive the water pump in case one of the breaks , BUT , the water pump is different , and the timing cover that holds it is too, the plus side is the newer pump has huge bearings to take the load of the extra belts , and the pulleys are the same size as the A/C pulleys , if I have to pull my pump in the future I will convert it to the new style , and extra it has a screw on fan clutch and lose that howling metal fan ,