Which "exhaust plate" are we talking about? The exhaust "baffle" plate is located under the exhaust manifold cover at the Port side of the powerhead.
The exhaust "adapter" plate is what the powerhead bolts down to.
If you can locate the Ser # of your motor, go to one of these sites and look up the parts breakdown diagrams for your motor. It'll give you a better idea of what you're looking for, along with parts numbers and pricing:
