2003-2004 Dodge 5.9L Cummins Built Transmissions

Complete 48RE and NV5600 units for the 2003-2004 Ram 5.9L Cummins

The 48RE fits 2003-2007 Ram 2500/3500 Cummins trucks, weighs about 248 lb and is rated for 560-570 lb-ft of input torque from the factory. That rating is tight enough that the engine was detuned behind the automatic. With the right aftermarket parts, though, the 48RE can be built to handle substantially more horsepower and heavier loads. That is what a complete package is: a case built up with stronger internals and, in most of these listings, a converter matched to it. The NV5600 six-speed manual was paired only with the High Output 5.9L from 1999 to 2005 and was retired by 2006.

When a complete unit makes sense

A tired stock 48RE usually tells you. The intermediate band stretches and loses material by 120,000-150,000 miles, which shows up as a flare between shifts, delayed engagement and burnt fluid. The factory converter has limited clutch area and a cast apply piston that deflects during lockup, so lockup slips and temperatures climb while towing. You can rebuild one part at a time, but a complete package gets you the converter, valve body and hard parts as a matched set. If your power goal is past about 500 hp, make sure the package has a billet input shaft; stock shafts have snapped with as little as 500 rwhp.

What we carry

BD Diesel builds most of the units here: 48RE Transmission and Converter Packages in several build levels, including a 4WD-specific version, the Roadmaster 48RE with converter, and the Towmaster 48RE with a billet input shaft. ATS Diesel Performance offers its 48RE Transmission Package for 2003-2007 trucks and an NV5600 Performance Manual Transmission for 2000-2005 trucks. Builders rate these packages by horsepower stage, so match the unit to your power and towing, not just the year of your truck.

Fitment notes

Early 2003 standard-output trucks, VIN 8th digit '6', may have the 47RE instead of the 48RE. A 48RE converter fits a 47RE but not the reverse, and the neutral safety switch connectors differ: 3-prong on the 47RE, 5-prong on the 48RE. 2003 and early 2004 trucks use a mechanical throttle-valve cable; the electronic TTVA arrived with the 2004.5 trucks. Output shafts differ between 2WD and 4WD, which is why some packages are listed by drivetrain. The NV5600 package is for High Output trucks only. Verify by VIN before you order.

Frequently asked questions

Will a 48RE package work in a truck that came with a 47RE?

Check before you buy. The two share gear ratios, but the neutral safety switch plugs are different, 3-prong versus 5-prong, and converters only interchange one way, 48RE into 47RE. Call us with your VIN and we will confirm what your truck needs.

Is there a built option for the six-speed manual?

Yes. ATS offers an NV5600 Performance Manual Transmission listed for 2000-2005 trucks. The NV5600 was only paired with the High Output engine, VIN 8th digit 'C'. G56 parts belong to a different gearbox that did not arrive until 2005, so they do not apply here.

How do I choose between the BD and ATS 48RE packages?

Start with your horsepower and how much you tow, since builders rate these units by stage. Then compare what comes in the box: several BD listings include the torque converter, and the Towmaster adds a billet input shaft, which matters past about 500 hp. The ATS package is listed for 2003-2007 trucks.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.