Stupid Head Gasket Question

Part numbers for 1960-1980 slant 6 passenger car head gaskets. 1960 thru 1967 used gasket #1947578. 1968 thru 1980 used gasket #2843182. In 1968 Chrysler superseded the old number to the newer number. The #2843182 gasket was discontinued in 1996. Aluminum engine used #2128279 gasket.