Differences between 70/71 and 72 Darts

Hi all. I'm looking for parts for a 72 Dart and am having some issues. I thought 70-72 were the same for the most part, but now I see a lot of things listed for 70/71 and not 72, so this makes me think there's some big changes for 72, but I haven't figured out what they are. What's the differences in parts, especially body stuff, between the 70/71 Darts and the 72? What's interchangeable and what's not?