The weather strip channel on the front of the quarter glass changed in 73. My 72 has a 71 and a 73 quarter glass in it and that glass is the same. Just change the channel.
1967 thru 1976 Darts use the same door. So the quarter windows should all be the same.
Several changes in the 73-76 Door
Yes, the doors were the same 69-72 and the doors and glass changed a lot for 73-76. 68 doors closely match 67. 67 doors have unique parts in them also, but I don't remember if the 67 quarter glass was unique, I don't think so.