Mishimoto MMTC-DMAX-15SL Transmission Cooler for 2015-2016 GM 6.6L Duramax LML

Protect your Allison 1000 transmission from its #1 enemy — excessive heat.

The Mishimoto MMTC-DMAX-15SL is a direct-fit, high-performance transmission cooler engineered specifically for the 2015-2016 Chevrolet Silverado and GMC Sierra 2500HD/3500HD equipped with the 6.6L Duramax LML and Allison 1000 transmission. Whether you tow heavy loads, run a work truck, or push your Duramax on the street or track, this cooler delivers dramatically better fluid temperature control than the stock unit.

Why Upgrade Your Transmission Cooler?

Heat is the leading cause of Allison transmission failure. The factory cooler simply can’t keep up under real-world demands like towing, hot climates, or performance driving. Mishimoto’s stacked-plate design provides 67% greater core volume and 164% more external fin surface area than stock, allowing the transmission to run significantly cooler and extending the life of your Allison.

Key Features & Benefits

• Massive cooling upgrade — 67% larger core volume and 164% greater fin surface area vs. factory cooler
• Stacked-plate construction — Maximum durability and superior heat dissipation
• Direct-fit design — Reuses the factory mounting location with included brackets and hoses
• CNC-machined adapters — Easy connection to stock quick-disconnect lines or AN fittings
• Includes air temperature sensor relocation bracket — Clean, factory-like install
• Silver anodized finish — Clean, professional appearance under the hood
• Mishimoto Lifetime Warranty with Accident Protection

Technical Specifications

• Core Dimensions: 27.95" long × 5.78" tall × 1.25" thick
• Rows: 13
• Construction: Aluminum stacked-plate
• Finish: Silver
• Inlet/Outlet: Stock-style quick-disconnect (adapters included for AN conversion)

Vehicle Fitment

Direct fit for:

• 2015–2016 Chevrolet Silverado 2500HD / 3500HD 6.6L Duramax LML
• 2015–2016 GMC Sierra 2500HD / 3500HD 6.6L Duramax LML
• Allison 1000 transmission

Chassis codes: GMT K2HC / GMT K2HG

What’s Included

• Mishimoto stacked-plate transmission cooler
• CNC-machined quick-disconnect to hose barb adapters
• Stock-style quick-disconnect fittings
• Transmission hoses
• Air temperature sensor relocation bracket
• Mounting brackets & hardware
• Worm gear clamps
• Mishimoto Lifetime Warranty