67 owner's manual

[67conv6cyl]

I have a April first week built car, in the glove box from when I bought the car over 20 years ago is a original owner's manual (no doubt it's a original) it is a third edition witch is April 1967. On all other original cars that I have seen with april build dates (most later than mine)  have second edition manuals. My vin ends in 7N203208. Any body no why?