.................... Humans performed most processes so various anomalies exist.
I can certainly attest to this comment. My 67 4B LOS 396 that I have owned since 1980 has:
1- Double strike for the engine prefix (ghosting)
2- Misplaced year and plant code sequence in the VIN ( instead of 7L it is L7)
3- The last digit in the VIN stamp is a 1 and the VIN tag and hidden VIN is a 7
To show an interesting comparison and how human error James eluded to can be consistant at times, below are 2 pictures of 67 BB's from the LOS plant.
The one titled 'L7-vin' is a picture taken from my 67 4B car.
The one titled 'big block-from CGR' was taken from a CRG thread:
) that is close to my S/N and also stamped with the same errors...upside down and the 7L reversed with L7 but interesting enough is the way the gang stamp was held on an angle being top heavy and the bottoms faint impression. This tells me it may be the same person who stamped both blocks.