i will be using a longtail on saltwater only, and the company i was talking to named me the couple of parts on their longtail that was not galvanized, and one of them was the actual drive shaft. is there any way the saltwater could get to it and corrode and rust, or is it completely sealed? thanks for helping, i am a noob.

The only thing exposed is the shaft right behind the prop and the universals behind the motor. The rest of the shaft is enclosed. I run mine in mostly saltwater and nothing is wrong with mine. I rinse mine off after every trip though.