Bob's Component Resto, Part 26: The Battery
The date code 3K is for September of 1973, which is correct for my car because it was built in mid-October of 1973 (for the 1974 model year). Battery dating back then was based on a letter of the alphabet representing the month of manufacture, and the number after the letter was the last digit of the year of manufacture. The letter sequencing began with the month of October, represented by the letter "A". September is eleven months after October from the previous year, and the letter "K" is the eleventh number of the alphabet. That's how you get a date code of 3K. Hope this helps.