Thermostat help

Received a Beck Arnley t stat today. I'm draining old coolant and replacing with new. Figured while I was at it i would replace the t stat as well. On the notes section in the picture I included you can see where it says that no seal or gasket. Well when I opened it, I saw what appeared to be an o ring seated in there. It doesn't look like the beefier o ring I ordered for it that isn't here yet though.

 

Here is the fel pro gasket that I ordered. Looks to be like the same thing that is already seated on the tstat that I have. Another question is, is there any sort of gasket that goes between the housing and block?