Went to replace thermostat and noticed the housing did not have a gasket installed. The thermostat did have a ring seal around it. Do I need a gasket seal for housing or does the ring seal on thermostat do the trick?

3.3L 6 cyl

 

should have been on on the thermostat itself

 

It was on the thermostat, a o-ring type seal. Problem I am having is finding a new o-ring. The don't come with the new thermostat, and none of the parts stores have a separate listing for the seal. Plastic housing leaks with out seal and old seal is disintegrating.

 

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