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?

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma