We have the 76 Bayliner Skagit and see that the exhaust flapper is missing. I have included a couple pictures of the exhaust port and the screw holes. If anyone knows where I can find one of these I would be truly grateful.....
You are not going to find the original style.
You can make one for a VP290 outdrive work though and you will need to modify your lower unit slightly.
On the bottom of the exhaust outlet there is a bump that needs taken off.