I can't give a definate answer to your question, but my Sears catalog sized factory shop manual was for 1972 (with points style ignition) and the much smaller supplement was for 73, which covered the electronic ignition, associated wiring diagram and a few other things such as changes in brakes, axles and so on. The same goes for the factory shop manuals for my motorcycles; a large primary manual for the first year that covers pretty much everything and smaller supplements that cover changes that are made in suceeding years. You might check closely because the manuals you described may only be the supplements. I can't remember which year was the first for the full time 4-wheel drive, but if it was 75 or 76, then that manual would cover all of the appropriate changes. Another example of something that would be covered in a supplement would be the different rear transmission mount used on my '77, which is totally unlike those shown in my older manual and supplement.
On the older supplement, on the lower right hand corner of the front cover it says "Starting supplement serial number XXX". If you can find out what that number is, it should give you an idea of whether or not your model is covered.