340 Wedge?
Yes, I think its safe to assume that there were many changes that were made during the production years on these cars, so finding different parts would be determined by stock availability and running production changes, not just model year. Another interesting feature of the 72 Demons I've owned is the cardboard headboard.
69signetv8 - I spent alot of time searching for photos of the grille I saw, and you know, the 69 Valiant style on yours does look like the one I recall. The boneyard example certainly could have been swapped, although the rest of the car did not appear to have any modifications so I assumed (and you know...).
Of course, here in Canada, stranger things have happened. Just ask the Alberta boys about all them 71 340 Darts they got..lucky b%^$^ds!