Josh,
Look at the year/month/day code as suggested above. It is in that format Y/M/D. Example 9M21 This is the 9th year or 1969 if it is a 1960s engine, M is the Month, or December of that year, They don't use ( i because of confusion with 1), and the last digits are the day of the month. So the example of 9M21 was built in 1969, December 21st.
The month goes A,B,C,D,E,F,G,H,J,K,L,M
A=Jan
B=Feb
C=March & etc.
This same year/month/day code should be on the heads inside the valve covers about the middle of them.
Ron
