Need help please!! 70 Dart trunk emblem

The way these cars were delivered seems to be in the wind. The only comment I have is; Stick with your Build Sheet! It does not lie. It does not always tell the whole story either. As I said above 2 of my 340 Swinger's had the Dart Swinger on the trunk and 1 did not. I bought all 3 cars from the original owners and none of them were likley to have modified the emblems. Oh well... The answer still eludes, Could it be the Plant they were built at? The Dealer? The build date? hmm......

Later,
Bruce B.