You might also try RTV silicone rubber compounds, catalyst addition cure and condensation cure silicone, tin catalyzed silicone, platinum catalyzed silicone, Silicones Inc. in South Carolina. Their price for a gallon of platinum-cure RTV (best for longevity and high heat) in P-20 formula (20 is the durometer) was quoted to me recently at $105.00 not including shipping. Call 336-886-5018 for ordering and pricing as they don't show this on their website. Gary in the technical department was very helpful.