{"product_id":"inmotion-ws8181na-differential-pinion-seal-rear-or-rear-outer","title":"InMotion WS8181NA Differential Pinion Seal - Rear or Rear Outer","description":"\u003ch2\u003eInMotion WS8181NA Differential Pinion Seal\u003c\/h2\u003e\u003cp\u003eThe InMotion WS8181NA differential pinion seal is built with nitrile material to create a secure barrier at the pinion area and help keep contaminants out of the differential. It is a direct-fit sealing component for select Ford and Mercury rear axle applications, including Mustang, Cougar, Pinto, Bobcat, Monarch, Montego, Capri, and Villager models.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eNitrile construction for dependable sealing performance\u003c\/li\u003e\n\u003cli\u003eInside diameter: 1.812 in.\u003c\/li\u003e\n\u003cli\u003eOutside diameter: 2.627 in.\u003c\/li\u003e\n\u003cli\u003eThickness: 0.455 in.\u003c\/li\u003e\n\u003cli\u003eShaft diameter: 1.812 in.\u003c\/li\u003e\n\u003cli\u003eHousing bore: 2.623 in.\u003c\/li\u003e\n\u003cli\u003eFits rear and rear outer differential pinion applications\u003c\/li\u003e\n\u003cli\u003ePart number: WS8181NA\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFitment Details\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eFits 1975-1978 Ford Pinto, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1971-1974 Ford Pinto, rear outer, with 6.75in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1964-1973 Ford Mustang, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1967-1972 Mercury Cougar, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1975-1978 Mercury Bobcat, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1975-1978 Mercury Monarch, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1974 Mercury Montego, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1971 Mercury Montego, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1972-1973 Mercury Montego, rear, with Ford axle.\u003c\/li\u003e\n\u003cli\u003eFits 1968-1970 Mercury Montego, rear, with Ford axle.\u003c\/li\u003e\n\u003cli\u003eFits 1967 Mercury Capri, rear, with 8in ring gear.\u003c\/li\u003e\n\u003cli\u003eFits 1966-1967 Mercury Villager, rear, with Ford axle.\u003c\/li\u003e\n\u003cli\u003eFits 1966 Mercury Capri, rear, with Ford axle.\u003c\/li\u003e\n\u003cli\u003eFits 1962-1965 Mercury Villager, rear outer, with 7.25in ring gear.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eDetailed Description\u003c\/h2\u003e\u003cp\u003eWS8181NA is a differential pinion seal engineered for select Ford and Mercury rear axle assemblies. Its nitrile sealing material helps maintain a tight interface at the pinion opening, reducing the chance of gear oil leakage while limiting the entry of dirt and moisture into the differential. This makes it a practical replacement for service work on classic Mustang, Cougar, Pinto, and Mercury rear axle setups where correct seal dimensions matter.\u003c\/p\u003e\u003cp\u003eThis part cross-references Monroe Shocks \u0026amp; Struts (e.g., 172286, 182286) for the same application. For buyers searching by application, this seal is a strong match for Ford Mustang rear differential pinion seal replacement, Mercury Cougar rear pinion seal service, and Ford Pinto rear outer seal applications with the listed ring gear and axle configurations. The part number WS8181NA is also useful when verifying the correct seal against existing service records or removed components.\u003c\/p\u003e\u003ch2\u003eCommon Issues This Seal Can Address\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eGear oil seepage at the differential pinion area\u003c\/li\u003e\n\u003cli\u003eContamination entering the differential housing\u003c\/li\u003e\n\u003cli\u003eWear-related sealing loss on older rear axle assemblies\u003c\/li\u003e\n\u003cli\u003eMoisture intrusion around the pinion opening\u003c\/li\u003e\n\u003cli\u003eService replacement for deteriorated or hardened original seals\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eInstallation Notes and Tips\u003c\/h2\u003e\u003cp\u003eConfirm the axle configuration, ring gear size, and pinion seal dimensions before installation. Clean the housing bore and shaft area thoroughly, and inspect the pinion surface for wear or scoring that could affect sealing. Proper alignment during installation is important to avoid damaging the nitrile sealing lip and to help the seal seat evenly in the housing.\u003c\/p\u003e\u003ch2\u003eQuality Assurance\u003c\/h2\u003e\u003cp\u003eInMotion manufactures this seal with precision-focused construction and high-quality materials to support reliable differential sealing performance. The WS8181NA is specified for the listed Ford and Mercury applications and is built to help maintain a secure seal in rear axle service.\u003c\/p\u003e","brand":"InMotion","offers":[{"title":"Default Title","offer_id":52406888333493,"sku":"HKKS-WS8181NA","price":8.25,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0628\/1442\/1173\/files\/WJ_WS8181NA_Fro2.jpg?v=1777774772","url":"https:\/\/www.partcatalog.com\/products\/inmotion-ws8181na-differential-pinion-seal-rear-or-rear-outer","provider":"PartCatalog","version":"1.0","type":"link"}