This looks like you an older style Wright operator, which is unfortunately no longer available. I'm not sure what to recommend, to be honest. I can't see what type of end bearing is on the end of the arm, and I am not sure about the length of the arm, either. That said, take a look at the
39-336 with the metal end bearing of the
39-028E with the nylon end bearing. Carefully go over our pictures and dimensions and let me know what you think.