Have asked before and no I have not seen these gaskets on any Weatherpack website or vendor. Just noticed the never used pigtail for an under hood light takes the same blue gasket as the engine temp sensor. Where can these and others used in these wiring harnesses connections be found?

 

I don't know if you can get those but they do come with new wiring plugs , or you can get some from the wrecking yard .

 

They are "automotive connector seals". They can be a bit difficult to find on their own, or in an assortment of sizes. But I'm sure if you look hard enough, you could find some. Here is a listing for a multipack of connectors and seals on amazon, it might help get you started on your search.