This is a 79 sea ray sedan bridge, I/B twin 255's freashwater cooled. I was changing the exhaust manifolds, spacers and risers (or elbows as Ive been calling them). Between the elbow and the spacer (a 4" spacer to allow clearance) one side, the left side on the starboard enging, had a stainless plate closing off the water jackets, the other side did not. Shouldn't both sides be plated off. I would think the raw water and the cooant would mix if left open. I was thinking someone just left out the thin plate when they last changed the risers. Could this be right? I'm going to do some more digging but need your help. Thanks