68 sway bar vs 73 sway bar

I'm currently looking at buying a sway bay on here. The seller advertised it as a 68 Dart at first. I would be putting it on a 68 B'cuda. So all is well. Then, someone points out that it looks like a 73 up sway bar. The seller is selling for a friend, checks with friend and verifies that it is a 73. Such honesty is refreshing in this day and time. My question is: What is the difference and will it fit ok on my car?
Thanks - Jim