Manual Transmission Output Shaft Seal by National®. Width: 0.47″. Inside Diameter: 1.5″. Outside Diameter: 2.381″. Housing Bore: 2.377″. Flanged Outside Diameter: 2.55″. Don’t just repair a leak, prevent future problems with a National Oil Seal. This part is manufactured using exclusive National Dynamic Edge technology that generates a dynamic pumping action to keep harmful contaminants such as dirt, moisture, etc. out of the seal and other wheel-end components.