Can I use my heating ductwork for an evaporative cooler?

I have an old Sear's swamp cooler, model #661.626920. I need to replace a louver, part #30214-01. Sears no longer has that part in stock. Can anyone help me locate this part?

I have an older model swamp cooler hooked to the outside of the house. Because of my fathers passing this is my first year to set it up and get it ready. I have it figured out for the most part, but I am stuck on where to hook up the float device. My mother thinks it goes on the water line to somehow turn the water off when it gets to full. I believe it screws to the side of the cooler and in essence lets the excess water drip out when it is over full. Neither one of us are sure we are right, and I can't find anything online to tell me. If it does somehow hook up to the waterline going into the cooler, how and where? If it doesn't where does it go and how does it work? Please help! We are sweating to death!