{"product_id":"gm-genuine-parts-ls-rear-block-cover-12639250-oem-rear-main-seal-housing-factory-fit","title":"GM GENUINE PARTS LS Rear Block Cover 12639250 — OEM rear main seal housing, factory fit","description":"\u003cp\u003e\u003cstrong\u003eGM Genuine Parts 12639250 LS rear block cover is a factory-engineered replacement that restores original fit, sealing and alignment for GM LS-series engines.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThis rear block cover (also known as the rear main seal housing cover) is produced and validated by GM engineers to meet the specifications used during original vehicle assembly. It’s intended for owners, technicians and engine rebuilders who need an authentic GM part that matches factory geometry, material choices and mounting locations. The part helps maintain proper crankshaft sealing and accessory alignment when replacing the rear main seal or servicing the back of the engine block.\u003c\/p\u003e\n\n\u003ch3\u003eWhat does this rear block cover replace and why choose the GM part?\u003c\/h3\u003e\n\u003cp\u003eThe 12639250 replaces the original rear main housing cover on compatible GM LS-family engines, ensuring the same bolt pattern, bore sizes and sealing surfaces as the vehicle’s factory component. Choosing GM Genuine Parts reduces fitment guesswork during installation and avoids modification that can cause leaks or misalignment.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eOEM dimensions and mounting points for direct replacement\u003c\/li\u003e\n  \u003cli\u003eManufactured and tested to GM engineering standards\u003c\/li\u003e\n  \u003cli\u003eBacked by General Motors for compatibility with Chevrolet, Buick, GMC or Cadillac vehicles\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow does this part help during an engine service or rebuild?\u003c\/h3\u003e\n\u003cp\u003eWhen you service the rear main seal or remove the crankshaft, replacing the rear block cover with an OE-equivalent housing ensures sealing surfaces are correct and any locating features match the block and seal. That reduces rework and helps achieve a reliable sealing surface for the new rear main seal.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eProvides proper seating for rear main seal installation\u003c\/li\u003e\n  \u003cli\u003eMaintains crankshaft alignment and torque specifications\u003c\/li\u003e\n  \u003cli\u003eMinimizes risk of oil leaks from mismatched or worn housings\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWill this cover fit my engine and what should I check before ordering?\u003c\/h3\u003e\n\u003cp\u003eCompatibility depends on the specific LS-series engine variant and vehicle application. Confirm part number 12639250 against your vehicle’s VIN, parts catalog, or a trusted dealer fitment search before purchase to ensure correct match.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eVerify using the vehicle VIN or year\/make\/model with a GM parts database\u003c\/li\u003e\n  \u003cli\u003eCompare bolt pattern and mating face to the removed cover if possible\u003c\/li\u003e\n  \u003cli\u003eCheck for any updated superseding part numbers from GM before installation\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat materials and quality checks make this an OE-quality choice?\u003c\/h3\u003e\n\u003cp\u003eGM Genuine Parts are engineered and validated by GM to meet design tolerances of the original assemblies. Materials and machining are selected to withstand engine operating conditions and to interface correctly with seals and fasteners used by GM during production.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDesigned and validated by GM engineers for OE fit and function\u003c\/li\u003e\n  \u003cli\u003eManufactured to rigorous GM testing and production standards\u003c\/li\u003e\n  \u003cli\u003ePart of GM’s continual updates to integrate improved materials and techniques\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for: This part is aimed at professional technicians, independent shops, and vehicle owners performing maintenance or full engine rebuilds on GM LS-series engines who want an exact-fit, factory-backed rear block cover. It’s especially useful when replacing the rear main seal, correcting leaks, or ensuring correct alignment during crankshaft or transmission service. If you need guaranteed compatibility with GM assembly geometry and prefer parts engineered by the vehicle manufacturer, the GM Genuine Parts 12639250 is designed for that purpose.\u003c\/p\u003e\n\n\u003cp\u003e\u003cem\u003eNote: Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE). Always verify fitment prior to installation.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eSome GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE)\u003c\/li\u003e\n  \u003cli\u003eGM Genuine Parts are designed, engineered and tested to rigorous standards, and are backed by General Motors\u003c\/li\u003e\n  \u003cli\u003eGM Engineers design and validate OE parts specifically for your Chevrolet, Buick, GMC, or Cadillac vehicle\u003c\/li\u003e\n  \u003cli\u003eGM regularly updates production and service part designs to integrate new materials and technologies\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Is part 12639250 an exact OEM replacement?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes — it’s produced to GM specifications for direct fit and original mounting geometry.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can I install this cover when replacing the rear main seal?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes — it’s intended for rear main seal service and ensures proper sealing surfaces.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"GM GENUINE PARTS","offers":[{"title":"Default Title","offer_id":48081422549150,"sku":"B00F677EHE","price":126.17,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/gm-genuine-parts-rear-block-cover-front-view.jpg?v=1785803611","url":"https:\/\/northtrailauto.ca\/products\/gm-genuine-parts-ls-rear-block-cover-12639250-oem-rear-main-seal-housing-factory-fit","provider":"North Trail Auto","version":"1.0","type":"link"}