RTS LubeLocker differential gaskets make paper gaskets and RTV a thing of the past by manufacturing high-quality, aluminum core gaskets with an outer silicone coating. The real secret to LubeLocker's success, however, is the elastomer beading applied to the gasket face. This beading provides a dry, leak-free seal, even when exposed to high horsepower, differential and axle flex, or wide temperature extremes. Drag racing, Circle Track, rock climbing, off-road, desert racing--it doesn't matter, LubeLocker differential gaskets will keep your lube where it belongs. Note: To complete the job as per factory fitted use RTS-N1903 copper washer and nut kit Differential Case Design Type: Ford 9 in. Gasket Material: Silicone/Aluminum Thickness (in.): 0.045 in. These gaskets compress to 0.025 in. thickness once installed.