What is this space? Exhaust maybe?

[Racer67]

Trying to figure out where this area goes to or what it's for? Right behind the water pump area. Thinking it might be for the exhaust.
It had a rubber gasket, but it's split Would I be in large if i run it without one or use the split one?
Thanks!

http://postimg.org/image/iwjgvw82x/

 

[racerone]

That would be where the exhaust exits the motor.----Seal should be in stock at most dealers.