what year service manual 73 or 74

Whats the 6th digit of the VIN? that tells you what year the car is.
The manufacture date is just that,the date the car was built, not the model year. Why would you buy a 73 manual when the car is a 74 or vise/versa?
There is no set rule about cut off dates for model years. Mopar was building 1995 Neon's in Feb 1994.
BTW, I see them all the time at the bigger swap meets. They come in 3 parts. The 1st is a mechanical manual, 2nd wiring and body, the 3rd is a TSB book. the 3rd is often over looked and is smaller than the other 2. It was published a year later than the others, but is damn handy.
I see them alot at Chevy shows, which is cool because they can be had cheap there.