I wanted to install the defrost fans before the windscreen as that would have been much easier, but timing precluded that. I originally purchased 4 in fans from Mouser Electronics, but thought they were too large. I purchased 3 in fans and mounted them instead. I place doubler plates under the fans. I used the doubler plate as a template where to place the holes. I then drilled around the perimeter of the hole in the doubler plate and snipped out the circle of aluminum. I filed smooth the edges, riveted the doubler plate to the glareshield. I plan to use flush mount screws to attach the cover over the fan.
