how close would a 98 Factory Service manual be to a 96? I know the redesign was in 97 so its a "different" model, but exactly how different would you say they are? How much interchangeability is there?
96 would have the old body style, with single airbag instead of dual airbags. It would have OBD-II and the new transfer case output.
But someone (RichP?) just noted that there were numerous wiring changes going from 1997 to 1998, so I don't think a '98 FSM would be a good choice for you.
You will also find that the 96 model also has some early changes installed into the body that were designed for the 97 model year; such as the hole in the drivers side fender where the windshield washer bottle penetrates, some body strengthening and a few other items.