RJSPHH Allison transmission cooler hose & fitting kit — 2006-2010 6.6L LBZ/LMM Duramax, factory-fit leak-resistant

Replacement Allison transmission cooler hose and fittings designed specifically for 2006–2010 GM 6.6L LBZ/LMM Duramax trucks with Allison transmissions. This RJSPHH kit provides the hose and fittings needed to replace aging or leaking transmission cooler lines on compatible Chevrolet and GMC heavy-duty trucks. Built to match the factory routing and connection points for the Allison transmission, the kit addresses a common failure point on 2500/3500 HD models powered by the 6.6L Duramax from 2006–2010. The components are made to restore a secure, leak-free connection between the transmission and the cooler, helping to maintain proper fluid flow and prevent messy, performance-affecting leaks.

Will this kit fit my 2006–2010 Chevy or GMC 6.6L Duramax with an Allison transmission?

Yes — the RJSPHH assembly is intended for 2006–2010 GM 6.6L LBZ and LMM Duramax diesel engines when paired with an Allison transmission. Confirm your truck year, engine code, and that it uses an Allison transmission before ordering. It does not fit vehicles with non-Allison transmissions or other engine variants.

• Compatible models: 2006–2010 Chevy Silverado 2500/3500 HD
• Compatible models: 2006–2010 GMC Sierra 2500/3500 HD
• Engine codes covered: LBZ and LMM 6.6L Duramax
• Transmission: Allison only — check vehicle build sheet

How does installing this cooler hose and fitting kit help my truck?

Replacing worn or cracked transmission lines prevents fluid loss and contamination while restoring proper cooling circulation. A secure hose and correctly sized fittings reduce the chance of sudden leaks, helping preserve transmission life and keeping the undercarriage cleaner. Installation returns the system to factory-style routing and connections.

• Stops drips and fluid puddles under the truck
• Maintains correct transmission fluid flow to the cooler
• Prevents contaminants from entering the transmission system

What’s included and what should I expect during installation?

The kit bundles the hose lines and matching fittings designed to replace the original cooler connections. Installation typically requires basic hand tools and moderate mechanical skill; some users opt for professional installation to ensure leak-free torque specs and proper routing. Inspect attachment points and clamps, and replace any worn connectors during the job.

• Kit contains pre-shaped cooler hose lines and compatible fittings
• Follow manufacturer torque and sealing recommendations
• Allow time to drain and refill transmission fluid after replacement

What materials and quality features should I expect from the RJSPHH kit?

The kit components are manufactured to fit OEM-style locations and connections, using hoses and fittings that withstand transmission fluid exposure and road conditions. While not a factory part number from GM, the pieces are engineered to meet the same fit and function standards for this specific truck family. Regular inspection after installation is recommended to verify long-term sealing.

• OEM-pattern hoses routed to match factory layout
• Durable fittings compatible with Allison transmission ports
• Engineered for transmission fluid compatibility and road durability

Who is this for? This RJSPHH Allison transmission cooler hose line fitting kit is aimed at owners of 2006–2010 Chevrolet Silverado and GMC Sierra 2500/3500 HD trucks with the 6.6L LBZ or LMM Duramax who are seeing leaks, swollen hose ends, or degraded fittings at the transmission cooler connections. It's a practical choice for DIY mechanics wanting to restore factory-style lines and for shops performing routine maintenance or repairs on the Allison-equipped drivetrain. Always verify engine and transmission type before purchasing to ensure compatibility.

FAQ

Q: Does this kit fit non-Allison transmissions?

A: No. This kit is made specifically for Allison transmissions used in 2006–2010 6.6L LBZ/LMM Duramax trucks.

Q: Will I need extra parts to install the kit?

A: Basic installation usually requires only standard hand tools; replace any worn clamps or seals you find during the job.