My 1980 Crossle 40f did not come with an air dam behind the radiator when I bought it. During my first race in the heat last season, my feet got so hot I ended up making one out of cardboard to get through the weekend. Since then I’ve seen several different versions made out of aluminum, fiberglass, and even carbon fiber. I ended up using a fiberglass piece available through Porter Racing. The first two pics are of the one I just installed, following them are examples of others I’ve seen at the track.