5.9/6.7 Cummins Transmission Cooler | Mishimoto MMTC-RAM-03SL

Keep a 2003–2009 Cummins automatic cooler under tow and heat with a larger stacked-plate core. Mishimoto MMTC-RAM-03SL is a direct-fit transmission cooler for Ram 2500/3500 (and 2008–2009 4500/5500) trucks with a 5.9L or 6.7L Cummins. It sits in the factory location between the intercooler and radiator, adds 212% more core volume and 244% more fluid capacity than stock, and replaces the corrosion-prone quick-disconnect fittings. The stock thermostat can fail closed and send hot fluid back to the transmission. This cooler uses a serviceable thermostat you can replace or bypass for full-time cooling.

Key features

• Direct-fit stacked-plate transmission cooler
• 212% increase in core volume vs. stock
• 244% increase in fluid capacity vs. stock
• Serviceable thermostat for faster warm-up in cold weather
• Included thermostat bypass plug for constant cooling
• Eliminates factory quick-disconnect fittings
• 6061 aluminum core
• Fits with a Mishimoto radiator and intercooler
• Mishimoto lifetime warranty

Fitment

• 2003–2007 Dodge Ram 2500 / 3500 5.9L Cummins
• 2007.5–2009 Dodge Ram 2500 / 3500 6.7L Cummins
• 2008–2009 Dodge Ram 4500 / 5500 6.7L Cummins
• Automatic transmissions: 47RE, 48RE, and 68RFE

Does not fit manual transmissions. Stock lines must be cut to remove the factory quick-disconnects. For AN braided lines, add two Mishimoto MMFT-8ORB-8BK fittings and a compatible line kit such as Full Send Diesel FSD-11-B or FSD-11-BE.

What’s in the box

• Mishimoto stacked-plate transmission cooler
• High-pressure transmission cooler lines
• Removable thermostat
• Thermostat bypass plug
• 2 CNC-machined stainless steel barbed fittings
• 2 CNC-machined aluminum 3/4"-16 ORB to hose-barb fittings
• 6 worm-gear clamps

AN adapter fittings and a full braided line kit are not included.

Notes & specs

• Brand/part number: Mishimoto MMTC-RAM-03SL
• UPC: 811580033513
• Patent: D912701
• Material: 6061 aluminum
• Core: 48-row stacked plate
• Core size: 26 in L x 10.94 in H x 0.87 in thick
• Fitting size: 3/4"-16 SAE ORB
• Fluid capacity: about 0.767 qt
• Capacity increase: about 0.88 qt
• Finish: silver / raw
• Install notes: intercooler typically comes out; factory lines are cut and spliced
• Install time: about 2 hours
• Warranty: Mishimoto lifetime

Top off with the correct ATF after install and check for leaks at idle and under load. If a 2003–2009 5.9 or 6.7 Cummins is cooking the 47RE, 48RE, or 68RFE on the highway or the trailer, Mishimoto MMTC-RAM-03SL is the factory-location cooler built for that truck.