I have a set I used to use held together by roller chain with bolts through the chain middles into the grousers. They worked but loud and somewhat fragile as I had the chain break once with lateral torque. Currently on a skid in my barn as back up. I went to Liberty tracks and have almost 400 miles on them. Located in western Illinois. It would take a major effort to get to them unfortunately but not a lot of 15" stuff out there.