Dumb question but never done it. Where is this located on a 496 Mag (375 HP)? How hard to change?

bikinilover, I just change the sea water impeller on sdelim25 496HO. It is on the left side as you look at the motor, way on the bottom. We had to pull the seat for easier access. It is a pain in the a$$ to get off the back side bolt. You have to loosen the fuel pump, and move out of your way. It takes a couple of hours and is not any fun, but that's boating. Or you could take it in and pay to have it done.

Thanks! I just ordered two of them. It is always good to have a spare in the boat.