[djpateman]

I have been researching these production numbers for a few years. The factory originally stamped the VIN in the same location, then changed to the production number in 1969 model year; coincident with the long wheelbase introduction. It is partly code, and partly serial #.
The first digit: 0=replacement body, 1=production body
second digit: 0=coupe, 1=Targa, 2=Karmann coupe, 3= Karmann 914/6
third digit: last digit of model year; this cycles 0=1970, 1980 etc
last four digits are the serial #

For example, 0=coupe could mean the car could be a 911T, 911E, 911S, 911RS or even 912 depending on the year. No differentiation for left or right hand drive, sunroof or anything else really.

The factory does have the number in most of the records, but not for 1969 I understand. The factory generally only reveals that the production # and VIN # that you provide them with do match or do not match. They are very security conscious about this #.
I have a good list of these numbers, and if you are willing to provide me with the VIN that it matches, it would assist my research.
Dave