RADHLBNIU Rear Main Seal Kit for GM 4.8L–6.2L V8 — Die-Cast Aluminum Cover, Gasket & Hardware

RADHLBNIU Rear Main Seal Kit is a complete replacement cover kit that restores a leak-free rear crankshaft seal for compatible GM 4.8L–6.2L V8 engines. This kit includes a die-cast aluminum rear main seal cover, updated seal element, new gasket and installation hardware engineered to match OE fitment for a range of Chevrolet, GMC and Cadillac vehicles. It replaces part numbers 635-518, 12633579 and 12639250 and is designed for direct installation where the listed models and model years match. Always verify the original part number and vehicle fitment before ordering to ensure compatibility.

Which vehicles will this rear main seal kit fit?

The RADHLBNIU kit fits many GM trucks and SUVs with 4.8L, 5.3L, 6.0L and 6.2L V8 engines from specific model years. It covers popular full-size models commonly used for towing and daily driving; fitment varies by year and model so confirm your vehicle and part number first.

• Chevrolet: Tahoe (2012–2013), Suburban 1500 (2012–2013), Silverado 1500 (2013), Silverado 2500 HD (2014), Avalanche (2012), Express 1500/2500/3500 (2012–2014, 2018 where listed)
• Cadillac: Escalade ESV (2012)
• GMC: Yukon (2013), Sierra 1500 (2013), Sierra 2500 HD (2015), Savana 3500 (2012, 2014, 2015)
• Replaces OEM numbers: 635-518, 12633579, 12639250

How does this kit reduce oil leaks and crankshaft wear?

The kit replaces the entire rear main seal cover assembly with a die-cast aluminum housing and a revised sealing lip to help stop oil seepage around the crankshaft. A new gasket and included hardware create a tight, consistent clamp load, reducing the chance of gasket failure or uneven sealing surfaces.

• Die-cast aluminum cover resists warping and maintains flat sealing surfaces
• Updated rubber seal design for improved lip contact and durability
• New gasket and installation hardware for a secure, leak-resistant assembly

What comes in the box and what tools do I need?

The package contains the rear main seal cover, pre-assembled or separate updated seal, a replacement gasket and the necessary bolts for installation. Typical installation requires moderate mechanical skill and standard garage tools; some jobs may need engine support or transmission removal depending on the vehicle.

• Included: rear main seal cover, seal, gasket, installation hardware
• Tools commonly needed: torque wrench, socket set, gasket scraper, seal installer or driver
• Service notes: may require engine support and transmission separation on certain models

How reliable is the RADHLBNIU rear main seal kit?

The kit is manufactured to meet aftermarket quality checks and undergoes inspection and testing to confirm fit and sealing performance. While designed to restore proper sealing, long-term reliability depends on correct installation, surface prep, and matching the kit to the correct engine and year.

• Quality control and testing performed during production
• Durable materials chosen for resistance to heat and oil exposure
• Follow vehicle-specific installation procedures for best results

Who is this for If you own one of the listed Chevrolet, GMC or Cadillac models and are seeing rear crankshaft oil leaks or replacing a failed seal cover, this RADHLBNIU rear main seal kit is an economical repair option. It suits DIY mechanics and professional shops that need an OE-style replacement with a complete gasket and hardware package — just confirm your vehicle year and OEM part number before purchasing.

FAQ

Q: Does this kit replace part number 12633579?

A: Yes. This RADHLBNIU kit is listed as a replacement for 12633579, 635-518 and 12639250. Verify your original part number before purchase.

Q: Is the gasket and hardware included?

A: Yes. The package includes the rear main cover, updated seal, replacement gasket and installation hardware.