Crank Casting Number

I have found that the full part number will be stamped in a line on the counter-weight on the thin outside edge of the forged cranks, usually back a ways from the front.... However, I don't see them often on the 70's cranks, usually only on the 60's ones. I've seen a few of them over the years, but not enough to say what they did when, and give a definative answer as to the rhyme or reason.