I went to a bunch of places yesterday and couldn't find any place that sold double grooved pins. I even went to a place called Threads of Georgia, and all they sell is fastners, and they didn't even sell them. But they sold me some bolts with a long threadless shoulder and some nylon insert lock nuts that will work for now. I just found out that Grainger sells what I need. They call them "Clevis Pin, Grooved, With Two Rings." I'm going to try them tomorrow when I go out for my wheel chock and paddock stand.