65-74 MoPar Block Casting Numbers

On the slant six engines these numbers can be found on the passenger side of the block just below the head. For V8 engines these numbers can be found on the drivers side front of the block just below the head.

The engine casting number for the most part includes the build year and the engine displacement. It may also have an assembly date. The twist to decoding the assembly date may be as simple as 3-15 (March 15th), or based on the 10,000 day calendar (2787 = March 15 1969).

The letter before the number indicates the year
A=1965  B=1966 C=1967 D=1968 E=1969 F=1970 G=1971 H=1972  J=1973  4=1974
Example: B-273-A24 reads as a 1966 block with a displacement of 273 and built on October 24th