NUMBERS ON BLOCK
Hello there:
Casting dates are usually expressed this way, “C 18 4.” In this example, the “C” means the month of
March, “18” is the day of the month, and “4” is the last digit of the year. This last digit may mean ’64, ’
74, ’84 or ’94, so you must also check the other characteristics of the block to determine in which
decade and year it was made. Some parts have the decade and year cast on them; these identifiers
look like this: “C 18 84.” GM introduced new model years in September or October of each year, so
when you see a casting date of “L 16 7” for example, this indicates a casting date used in the 1968
model year because it translates into December 16, 1967. A 1968 model Camaro assembled on
January 6, 1968, might contain a number of parts that were cast in December, 1967. Casting dates
should precede hand-stamped engine assembly dates.
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