94-02 Dodge 5.9L Cummins 47RH/RE Randy's Fluidyne Heavy Duty Transmission Cooler

The Randy's Fluidyne RT-47-9402 is a heavy-duty transmission cooler built for 1994-2002 Dodge Ram 2500/3500 5.9L Cummins trucks equipped with the 47RH or 47RE automatic transmission - an upgrade over the factory cooler for owners who tow heavy, run a modified truck, or simply want more thermal headroom than the stock unit provides. This is a performance upgrade, not a stock-style replacement.

The RT-47-9402 fits both the 12 Valve 5.9L Cummins (1994-1998) and the 24 Valve 5.9L Cummins (1998.5-2002) with the 47RH or 47RE automatic transmission.

Why Upgrade the 47RH/47RE Cooler

The factory transmission cooler on these first and second-gen Cummins trucks was designed around stock power and light towing loads. When you're towing heavy, running in summer heat, or adding performance, fluid temps climb fast and stay high - and heat is the single biggest cause of early transmission wear on these platforms.

The RT-47-9402 uses a stacked bar-plate core that delivers four times the core area of a conventional tube-and-fin cooler design. More surface area means more fluid is exposed to the cooling airstream at any given moment. Combined with four times the fluid capacity of a standard cooler, the result is up to 20 degrees lower operating temps under load - the kind of margin that separates a transmission that survives 300,000 miles from one that starts slipping at 150,000.

If your goal is stock-level restoration with no performance gains, the factory-spec cooler is the correct path. This is the part to order when you want genuine thermal headroom for a working truck or a modified build.

Fluidyne Stacked Plate Design - What It Means for Your Transmission

Fluidyne's bar-and-plate construction is a fundamentally different cooler architecture than the tube-and-fin units found in most factory applications. Each cooling pass pushes fluid through flat stacked plates separated by fins, creating a dense grid of cooling channels that dramatically increases contact between hot fluid and cooled airflow.

The dual-pass flow path means fluid makes two complete runs through the core before returning to the transmission - maximizing heat extraction at every operating temperature. This is the same technology Fluidyne supplies to NASCAR racing programs, where consistent fluid temps under sustained high-load conditions determine whether a transmission survives a race or fails on the track. On a 5.9L Cummins tow rig or work truck, those same thermal management principles translate to cooler fluid on long grades, in stop-and-go traffic, and during extended PTO or fifth-wheel operation.

If your fitment and build goal match, the RT-47-9402 is the right cooler to order for this application.

RT-47-9402 Fitment Coverage

Fits 1994-2002 Dodge Ram 2500 and Ram 3500 trucks with the 5.9L Cummins diesel and the 47RH or 47RE automatic transmission.

Verify your transmission code before ordering - manual transmission trucks and other automatic applications are not covered by this part number.

Avoid These Common Mistakes

• Wrong transmission: This cooler is built for the 47RH and 47RE automatics only. Do not order for manual-transmission trucks or other automatic platforms on this generation.
• Missing the 1998 mid-year split: 1998 trucks built before mid-year carry the 12 Valve 5.9L with the 47RH. Trucks from 1998.5 onward use the 24 Valve with the 47RE. Both are covered by this part number, but confirm your exact build date and transmission code.
• Ordering without checking lead time: Randy's Transmission items carry a 20% cancellation fee after purchase. Call us first to confirm availability if lead time is a concern before placing your order.
• Expecting stock-style fit without any modification: This is an upgraded unit with a larger core than factory. Confirm mounting and line routing compatibility for your specific setup before ordering.

Before You Order - Final Checks

• Model year confirmed: 1994-1998 (12 Valve) or 1998.5-2002 (24 Valve)
• Transmission confirmed: 47RH or 47RE automatic
• Lead time and shipping availability verified with us before purchase
• Cancellation policy understood: 20% fee applies after order is placed

For a 1994-2002 5.9L Cummins Ram with the 47RH or 47RE and a real need for lower transmission temps under load, the RT-47-9402 is the correct cooler to order - confirm your transmission code, check lead time, and proceed with confidence.

Frequently Asked Questions