What are these called and where can I buy them?

I have a couple here. There are three different sizes that I have in the few that are here. I posted these picture for reference. You need to make sure you get the correct length. I do not have a 72 dart here at this time to put you in the right direction. You will have to get someone with a dart apart to measure theirs. I believe all swingers/ dart and scamps are the same from 67-72. Steve