Okay...after trying to read through the mega thread and archives, finally decided to just post some pics to get the correct answer about the cast impeller style/fins.
Some of the old threads don't really pinpoint which style is the correct one, so here goes...I am assuming the NAPA/GMP design.
NAPA - (aluminum body) -
https://www.napaonline.com/en/p/TWQN...put=water+pump
GMP - from Summit -
https://www.summitracing.com/parts/g...tiac/model/gto
Cardone
Autozone - (with limited lifetime warranty) similar design as Cardone -
https://www.autozone.com/cooling-hea...87_0?rrec=true
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1970 GTO (Granada Gold) - 400 / TH400