How to identify door years?
Oh I don't think I'm an expert, I've just seen a few of these things.
Here's a picture of the door impact beam, looks like '73's didn't get them (or at least not all of them). There's a little more information in this thread, although not all of it is correct. '74 is not a one year only door like suggested in this other thread
73 to 72 Dodge Dart door swap
I'll see if I have a picture of the lift mechanism somewhere