I just took out my original fans and installed new fantastic fans. I scraped off the old sealant used the gasket that came with it, screwed the fan down and then sealed around the outside frame where the gasket meets the housing/roof and the screw heads with tempro or vulcum. It can be found many different places like dealers, rv supply places and the factory. It's good to always have some on hand. I swapped them out in about 30 minutes each.