Detail about Trans. Filter Kit?
 

I installed a new transmission filter. In the package along with the filter and pan gasket were 3 metal seals. The 2 small ones looked like they go to the pan and TC plugs, and thats where I used them. There is a bigger copper seal and I have no idea what its used for. I am always suspicious of extra leftover parts. Where does this one go?

I've used these combo kits - filter, gasket, washers - mfg. was Meyle.

The only parts used were the filter and gasket of course + the 2 small washers - one for pan drain plug; the other for the converter drain plug.

Maybe the copper one goes to a cooling line? Oh well, I'm done with it so it goes in the doo-dad box.