By the distributor is the date the motor was cast (date code). That, along with the casting number (behind the passenger side head ) and th block code on the front will determine the year, size and FACTORY rated HP of the motor.
The date code is usually 4 characters - a letter and three numbers. The letter corresponds to the month, the next two numbers the day and the last number is the year (Where "9" = 1969 or 1979)
