Palmer M60 & P60 Marine Engines Engine Block* - Casting Date Stamp Codes: Sample: ‘’12 1 S’’ is Dec 1, 1971 A - 1955 1977 B - 1956 1978 C - 1957 1979 D - 1958 E - 1959 F - 1960 G - 1961 H - 1962 I - - J - 1963 K - 1964 L - 1965 M - 1966 N - 1967 O - 1968 P - 1969 Q 1947 - R 1948 1970 S 1949 1971 T 1950 1972 U 1951 - V 1951 - W 1951 1973 X 1952 1974 Y 1953 1975 Z 1954 1976 *International Harvester C-60 Engine Blocks