Rear Outer Differential Pinion Seal (8610) by National®. This product is made of high-quality materials to serve you for years to come. Designed using state-of-the-art technology and with customers in mind, this product by National will last a lifetime. It will meet your needs and deliver great quality at an affordable cost. 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.