This has gone eight pages without anyone here having the actual facts or firsthand knowledge of the actual situation.
What I have seen is a knowledgeable GM guy thought he was buying a numbers matching 340 Duster in what looks to be real nice shape for $9,000. How, exactly, was the car advertised? Did granny advertise it as numbers matching? Or was it simply asked of her, is the car original? It may very well be as original to her as when they bought it.
What I do not know is that it is a rebody. I have not heard or read any compelling evidence up to this point that says it is. A body man says it was repaired from two different cars. OK, but we do not know at this point which car was which do we? OP says core support numbers match but look hokey? I do not know what hokey means to OP. We have asked, explain it or show a pic; but I have not seen it. OP says it is a rebody, but he did not tell us which car was which. I have asked a couple of times about the door jamb sticker and what numbers might be on that - but no answer.
If the body man was being honest with this guy on the phone - that both Dusters were 340 cars... why rebody?
C