BlackGS answered my question by posting this picture over at Regal forum.

So it looks like the AC Delco water pump that Rock Auto shows #252-693 long #88926207 does have a cast impeller.

Just curious but would it be worth it to run even like a 5% UD WP pulley on a completely stock car? Maybe just for keeping your engine'* heat down while in traffic on a super hot day? I mean, I know that a stock, properly maintained cooling system should not even come close to overheating even in the most heat conducive conditions (i.e., combo of *&G traffic, super hot day, A/C running and possibly towing a trailer), but maybe just would keep the heat down a bit. A cooler engine is always better. But trying to weigh any cons against it. Price? Availability of mod? Major cons? (cavitation? etc?)

Just trying to gain some knowledge here.

There'* a fine line between running through the block quicker/slower and not spending enough time/too much time in the radiator to cool down.

My advice after doing it is not to. Not until you start modding and notice an increase in normal operating temps.

can you eleborate on this? i'm just curious

Thats understandable, less time in the radiator, basically recirculating hot coolant. So maybe in conjunction with the pulley, you could have either a fan override or just set the ECM/PCM to turn on the fans at a lower operating temp? Cooling down the radiator significantly more, making up for short time spent in the cooling ducts?

Does that change anything significantly or would it be more worth it to just install a fan override ALONE to battle high temps on hot days?

Thanks alot.

More load on your alternator is resistance to the belt travel. Which is driven by the crank. The alternator robs horsepower in order to keep up with demand. Increase demand, rob more horsepower.

Fan override alone would be more than sufficient. I didn't go with an UD pulley until last year, and it caused me to make further changes to my setup. Including a home-built Estat, and playing with thermostats/drilled holes to find the proper 'balance'. The net result is not a setup I'd drive in the winter. So I have to switch back and forth.