Seen if there is a part number stamped into the gasket. If they are oem Fords there will be a number. They came in both .015 and .020 thickness.The Mr Gasket steels are .020. There were a few different ones offered from Ford. Most of the 390's used the B9AE-6051-A gaskets that were .015. I have a NOS set of C8AE-6051-B .020's I don't need. They are for the 390/428bore size. If you need them pm me.

G.