I have several copper washer assortments from Harbor Freight, grabbed when on-sale. I throw spare aluminum washers in there too. I never worry about re-using them. If scuffed, I just sand the surface, though some here claim you must heat-treat them to restore. Mine don't leak.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans