DHD Dirty-Alli Hi-Performance 10L1000 Stage 1 Built Transmission | 2020+ GM 2500/3500HD

The DHD L5P Allison 10L1000 Built 10-Speed Stage 1 Transmission is engineered for 2020–2025 GM trucks equipped with the 6.6L Duramax L5P and Allison 10L1000 transmission. Designed for improved durability and performance, this upgraded transmission incorporates strengthened internal components and proprietary improvements to support diesel engines producing up to approximately 550 horsepower.

Each DHD transmission is built using a rigorous assembly process performed in a controlled environment to ensure precision and reliability. Every component is hot tanked, ultrasonically cleaned, and carefully inspected before assembly. Critical measurements, functional checks, and piston apply tests are conducted during the build process to verify proper operation before the transmission leaves the bench.

The Stage 1 build includes increased clutch capacity, a DHD hard anodized F drum, proprietary valve body modifications, and multiple new OEM components. These upgrades help improve clutch holding ability and overall transmission reliability while maintaining smooth operation for street-driven performance trucks.

• Vehicle Fitment: 2020–2025 GM 6.6L Duramax L5P
• Transmission Model: Allison 10L1000 10-Speed Automatic
• Power Rating: Up to approximately 550 horsepower
• Increased Clutch Capacity: Upgraded clutch packs for improved holding power
• DHD Hard Anodized F Drum: Strengthened internal component for added durability
• New OEM Torque Converter: Included for reliable operation
• Valve Body Improvements: New valve body with proprietary DHD modifications
• New Electronics and Wiring: Updated components for consistent performance
• Solenoid Stabilization and Testing: Verified for proper function
• Deep Transmission Pan: Helps increase fluid capacity and cooling efficiency
• New OEM Gaskets, Seals, and Torrington Bearings
• New OEM Sump Filter Included

Core Requirement: A rebuildable transmission core and torque converter are required for this product. To receive full core credit, the returned core must be rebuildable with no case damage, catastrophic failure, or broken hard parts. The core must match the model and type of the transmission received. Electronic functionality is not required, and the core may show signs of normal wear.

Note: Core charge and freight costs are additional. Transmission longevity depends on proper tuning, adequate cooling, and responsible driving habits. Excessive heat and repeated shock loads can reduce transmission life expectancy.