Re: merc 150 exhaust plate
I dunno if this site sells stuff like that, you can check it out here if you like.
If you don't find anything, try this place; they have parts lookups by HP and Serial #, with real good illustrations and part numbers.
http://www.mercruiserparts.com/SelectModelType3.asp?class_id=2
Be sure to get the gaskets that go with, and check the inner cover (if yours is not one-piece assy) for cracks/perforation. Torque the bolts to factory specs and recommend you pick up a manual for your motor.
HTH & Welcome to the iBoats forums!.........ed