Is it Rare? 71 Dart swinger 340 special

Hey all, as you can likely tell I’m new to this web so apologies if this is in the wrong thread! So I just made a post on Reddit and was directed here. Gonna give you a long story short but you can find the entire thing here:

anyways, I found an old dart in one of my grandads old yards, turns out it’s a 340 swinger from 71. Now I thought that was weird since the only made em in 69 and 70, turns out there was a special edition in 71 and 72 made in Canada. Looked up some numbers, not sure how accurate, but I could be looking at 1 of 85 ever made. How accurate is this? Any help appreciated!