Bullet Proof Diesel 6700013 Rear EGR Cooler is a direct-fit upgraded replacement for the factory rear EGR cooler on 2011–2014 GM 6.6L Duramax LML engines. It replaces GM part number 12635704 and is designed to address the well-known cracking and coolant-leak failures common on stock LML coolers.

The cooler uses Bullet Proof Diesel’s patented H-Core technology: helically wound (twisted) stainless-steel coolant tubes instead of straight tubes. The twist lets the tubes flex with heat expansion and contraction, which greatly reduces stress on the seams and bulkheads. The design also packs more tube surface area into the housing for more effective cooling of exhaust gases.

Key Features

• Stainless-steel tubing that is stronger and more resistant to fatigue and heat-stress failure than OEM
• Patented helical H-Core construction
• TIG-welded or vacuum-brazed tubes and bulkheads
• Quality-controlled for a precise drop-in fit
• CARB EO number D-730-6 (legal for use in California)
• Limited lifetime parts-only warranty

Fitment

• 2011–2014 Chevrolet Silverado 2500HD / 3500HD and GMC Sierra 2500HD / 3500HD with 6.6L Duramax LML
• VIN 8th digit = 8
• Replaces GM 12635704

Important notes: Gaskets and hardware are not included. For 2013–2014 trucks, confirm the cooler matches the pictured unit; some later LML rear coolers use a different configuration (check part 6700014 if it does not match). A refundable core charge typically applies.

This is the rear cooler only. LML engines use a two-cooler EGR system (front + rear). The H-Core design is intended to last the life of the engine when installed correctly and maintained.