New Starter

I lost my port starter (REVERSE ROTATION) I have a strong feeling that it was replaced earlier with one that worked but not correctly. My ring gear is ok but I want to purchase an original Starter. I would need guidance to a part number or a place to purchase one. My boat is a 1984 33.3 Commander- (2) 350 ci - 260 hp thunder bolt ignition - Any help would surely be appreciated -

Thank you

William Coleman Sr