Probably the best place is international parts counter. Thats what they supposed to use from the factory so I'm told. I do not know this for a fact so check around before you buy. What ever you buy just make sure you do not install an oil pan gasket because they will leak. Then you will have to pull the engine again to repair it. The factory used an RTV sealant. I use permatex ultra copper plus. It has never failed me after more years than I like to remember. Spray Hilomar on the head gaskets will make for a great sealed surface too. Three lite spray coats is all you need.