Does Mercury suggest a 140 or 160 thermostat in the 500 efi?

I ordered a thermostat and gasket and am installing today. The gasket was wrong and the thermostat was a 160. The one I pulled out was a 140.

Did Mercury screw up my order?

I think the difference is whther you have closed cooling or not. My cloed cooling system wants a 160---non-closed cooling wants 140

Poorsche