Why would you want the original body? There are a number of issues with the original kit, the first being incorrect front wheel openings. The hood was also too flat, because it was made to use the underside tooling from the Duster hood. If you have an original Demon and a Duster annual kit, the underside of the hoods in both kits are the same, the Demon's hood having the Duster center bulge on its underside.
That hood doesn't have the normal "cut line" engraved on the underside; instead, the whole cutout area is recessed, much thinner than the rest of the hood. Even just painting it can cause that area to sink in if you aren't careful. The way to fill the recess would be with a piece of plastic that would build the thickness up to that of the surrounding area (or maybe a little bit thicker). Attach that with either super glue or epoxy, grind it to the thickness of the surrounding area if necessary, then putty any gaps that appear. Make sure the "top" of the filler piece fits the underside of the recess area without leaving a gap. For hoods with the usual recessed cut line, if you aren't cutting out the hole it's a good idea to fill the line to help eliminate "ghosting" on the top side when you prime/paint. Thin lines can be filled with putty, thicker ones with thin strip styrene. Whatever cement you use, try to jam the strip into the cut line. After everything sets up, you can file/trim/sand to match the surrounding areas.
Ford did build some great high-performance Falcons...Ford of Australia, that is! If you've never seen them, do a search...they built some hot ones, with engines as big as the 351 Cleveland. Theirs were all four-door sedans, but the later ones based on the North American '66-'70 body had some great graphics and wheels. Their station wagons were different from ours too (better looking).
It's amazing too, the guys who don't have time to get your parts to you still manage to struggle to the bank to cash your check. Other than Modelhaus, I can't remember the last time I bought any aftermarket stuff by mail. Well, there was that order of photoetch sets that the incompetent mailman lost, stole, or mis-delivered, but that's another deal altogether. When I was in the business, the last day before leaving for a show I'd open the mail and make sure that I pulled items off of the stockpile and set them aside to fill those orders, so I wouldn't sell something out from under someone at the show.
All of the road test equipment was included only in the first two issues. The third one (original Grand Slam) deleted all of it. For that issue, the clear parts tree was trimmed back to only the window unit. The first two issues had a bunch of other clear parts including side glass, headlight lenses (including stock ones), and a "glass" fuel measuring bottle for the road test version. The Prestige issue returned the road test parts except for the fuel bottle because apparently the clear parts taken out earlier no longer existed. I gave the new Grand Slam issue boxes a brief look at a high-priced local shop; looks like the fuel bottle and the big vertical clear headlight shrouds for one of the custom versions have been retooled. I'll be picking one of these up, probably the expanded version in the larger box. The Grand Prix and Bonneville didn't share any parts other than tires and wire axles, though the engines, chassis, and interiors have a similar parts breakdown. The GP has some neat optional parts for the engine, including a GMC blower intake with an adapter that keeps the carbs under the hood.
The first issue of MPC's '57 Corvette was in 1966. Molded in white/off-white, seven versions (many of them using the same optional parts as the '60, first issued two years later). A stock version was included, but the rear wheel openings on the body have been radiused from day one. The first issue was called a "1956/57". MPC included unplated headlight buckets (main visual difference on a '56) in addition to the plated ones.
I had one of these sets. For some reason, some of the plastic parts deteriorated to a point where they would crumble when handled. It wasn't all of the parts, but it was either all of the "girder" pieces or all of the connecting pieces. Either way, the deteriorating parts didn't leave you enough to build anything afterwards. If my experience was typical, I'd bet most of these sets were tossed once that was discovered.
The guys designing kits at Ertl in that period were apparently being given more opportunity to express themselves and their knowledge through their work. It seemed like, at that time, they were trying to get something different into each new kit, and for a while they were doing just that. The DOHC setup in the Coronet, the Stage V hemi conversion parts in the '71 Charger street machine, and the Art Morrison chassis in the Wagonrod kit are only three examples. If you compare the "stock" and "street machine" versions of some of those newer tooling kits to one another, on second glance you'll often see a lot of little differences you may have missed at first.
AMT '60 Comet, mid-Sixties gasser...Olds powered, maximum engine setback and crankshaft centerline height per the rules of the day. The interior is gutted (front and rear seats originally molded in as a unit), exhaust detail removed from the chassis, everything from the firewall forward pretty much scratched. The body was a glue bomb, I spent a number of hours grinding out and sanding off glue, and filling accessory holes. The original steering box placement clashed with where the headers are going, have a new setup worked out but haven't gotten around to doing anything with it...
With the old annual kits, there was AMT and there was MPC. Two competing companies back then. If you want parts to restore an AMT annual ('70-'77) then first choice would be the AMT/Ertl kit (the backdated one). If you are restoring an MPC annual kit, you want an MPC kit. MPC annuals were produced through '81, there are a couple of non-stock issues of the later annuals that have all the chassis and engine parts. The chassis parts in the Round 2 '79 Trans-Am are the same too, though the exhaust system is a bit different. The ex-MPC Blackbird kits (those produced after 1980 or so) are similar to the annual kits but not exactly the same. MPC tooled that one later because the Blackbird was selling so well that they didn't want to stop producing them while still doing other versions like the 10th Anniversary T/A. The Blackbird chassis parts might work, most likely if you use the whole chassis rather than individual pieces. That's not to say that absolutely nothing from AMT will fit MPC, or vice versa...but more parts will interchange and be similar to the originals if you stay with the same brand. I haven't messed with either company's annual kits versus the newer '70 Z/28, so I can't kick in anything of value regarding its usefulness in rebuilding an annual. Generally, when I restore an annual kit, for some irrational reason I try to stay close to the kit's original configuration, flaws and all.
If you have one with wire axles and a one-piece interior bucket, it's an old AMT kit. Started out as a '70, updated through '77, issued as a T-roof version, then backdated to the '70 Z/28. That one didn't sell too well, so later Ertl tooled up another one from scratch...much better.