It could be a full or partial VIN. If partial, it will have the first and second characters of the VIN, and then the last 6 numbers. For example, if the full VIN is 0X91T167193, the partial VIN will be 0X167193. I don't know the rhyme or reason behind why they stamped the full VIN on some and the partial on others.
So does anybody know what's stamped on the block of my 302 just in front of the driver's side head? Edit: Nevermind, it's a date code.