Thermostat and gasket puzzel

"I am trying to replace the th

"I am trying to replace the thermostat in my mercruise 260/350 engine. I bought one new with a gasket set which is confusing. The parts are the correct ones for the engine but there is one gasket that would totaly close the thermostat hole. Why would one completely close the water flow?
Another thin gasket with oblong bolt holes would just close the square hole part above the thermostat. Isn't this a bypass for the exhast cooling before the thermostat opens? There is one that would not close the square hole ( my guess this would be at the intake manifold) and one smaller gasket(cork) that looks like it would sit under the thermostat lip. There is a rubber O ring the size of the smaller gasket. I have no guess on this one. This is a raw water cooling setup with four hoses from the lower thermostat housing and two hoses from the cap. There was no thermostat in the thing from the start so I don't have the old one to go by. The thermostat does go under the two hose cap and not on the intake manifold itself, right? I have a manual but it is totally useless about gasket details. Also when are restictor gaskets used on the exhaust and when not? This is a center riser setup. Any help out there for this puzzel?"

"Mark,

Not all the gaskets

"Mark,

Not all the gaskets in the kit are used. The kit works on many different models other than the model you have.
Only use the gaskets that are the same as the ones that you removed."

"Mark: Charli is right about

"Mark: Charli is right about the gaskets. You said there was no t'stat in the housing. You are probably missing the brass sleeve (spacer) that holds the t'stat in place. Go to this website and select your engine serial number and look at the cooling diagrams which shows all the parts and how it should be assembled.

http://www.mercruiserparts.com/selectModels3.asp?type_id=8

Guy"