Isn't it amazing just how many different combinations the 73-87 square bodies have among the different models, of course many things are the same. There are so many different styles of mirrors, bumpers, interior, rims, tires, trim, etc, etc, etc. And I could write a small book on how different under the hood can be among the models. Even the placement of the battery, windshield washer reservoir, air cleaner assy, etc, etc. The are so many trim package options, different size gas tanks, placement of the gas tank- white, grey or chrome bumpers, with or w/o padding, rally rims, hub, caps, large hub caps or dog-dish style hub caps. Solid paint or two tone, single or dual exhaust, 6 cylinder or a 454 big block! And how many different door panels are there, seats, dash options, dummy lights or gauges, black wall/white wall, chrome trim or no trim, ect, ect, ect! How did the factory workers keep up as they came down the line, they must have had a code sheet or something. HOWEVER, they still do that today. I bought my wife a new Nissan versa and there were several trim pckgs you could get, starting at the "base" model of course. I guess the build sheet tells it all.