Here you can see that the Date Code for these cylinder heads is D244. You will also notice that both heads match with the same Date Code. Why is this important? Because that means they are a matched set. The D represents the month of April. The 24 corresponds to the Day of the month, in this case the 24th of April. The 4 represents the year, 1964. Hence these two heads were created on April 24th, 1964.
