I may be losing my mind but I'm putting stuff back together after intake manifold replacement and I can't remember if there was a gasket other than the rim of the thermostat for the housing. I usually put gaskets and stuff that I took off with the part so I remember what stuff has to go back but all I have together is the housing and thermostat. It's a 99 burb w/ 5.7 L vortec. I only see an o ring like gasket on the Rock Auto website, which looks like the rim of the new thermostat I bought. Thanks for helping an old tired out brain.

 

Thermostat incoporates gasket made on it, @ least mine did. Your ok.
david

 

Thanks Justim. That's probably why I don't have one separate from the tstat. I just cant seem to remember some of this stuff.