The Date Codes for the 1958-65 348 and 409 cylinder heads can be found in between 2 valve springs either on the right or left side. CFD heads will have them on the right side.
Date codes can either be a combination of letters and numbers or whats known as a "Julian" date code which would be 1-3 numbers.
For more information on both types of date codes and how to read them, go to the Date Code page:
348/409 Date Codes
