Can't say for sure about a 63 and 66, but definitely a 64/65 Valiant or Barracuda. A Dart wagon is in reality a Valiant wagon with a Dart front clip on it.
The rear quarter is shaped different due to lead in of tail light lense and such. The Dart wagon bumpers are different on the sides and cut back a little different plus don't have holes to bolt to the end supports like a standard car, they use a rubber block that the bumper registers off of. I showed SlantScamp the difference with a Dart Wagon bumper and a standard as he was told they are all the same. I have both but will have to take a picture. It's easier to show the difference with pics of course and I hope it helps.
