Strictly an opinion Pascal but my experience says the best parts book to pick up for a particular car is the issue that is put out about one or two years after the model year of car you have. For example, I would look for a parts book published in about 67-68 for my 66 GP if I want the ideal book. When they are brand new, they may not have all the illustrations or all the part numbers for the year that they are published for.
Once you get one that is more than 10 years past the date of the car, for example a 1976 publication for my 66 GP, it may be missing some of the seldom sold part numbers, especially trim parts like plastic interior parts or soft trim stuff.
As I said, my opinion based on what I've seen.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
