Has anyone decoded their 340 serial number?

There is a 14 or 15 digit/letter stamping on the front of the block below the driver's side cylinder head. Anyone figured out all the numbers/letters? I have a service manual that supposedly explains everything, but the service manual states one of the numbers/letters designates the model of the vehicle. That's a new one on me. Half of the stamping on my block is blurry, might have to send it to forensic department of the FBI to read it for me.