Water pump direction 500HP vs 502 MPI

500HP w belt
502 MPI w serpentine belt

seems like they turn opposite direction due to the belt arrangement yet share a common part number...

Any info?

They should both turn clockwise when looking at the front of the motor. If for some reason it turned counterclockwise (reverse rotation motor say) then the part number is still the same, just the 2 raw water hoses on the back would be reversed.

Serpatine belt vs v belts alter the direction due to the path taken.

which pump do you mean .raw water or circulating??

I assumed you meant the raw water pump. Circulating pumps are Bidirectional I believe ( for the part number you're looking at ).