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03-04 Dodge 5.9L Cummins w/Auto Trans PacBrake PRXB Exhaust Brake

Fits: 2003 - 2004 5.9L 24 Valve - 48RE Auto Trans
(vehicles built up to Jan 4, 2004)
Early production 2003 model with 47RE automatic transmission, please call before ordering.

Includes transmission controller to fully utilize the potential of the exhaust braking force.

Works with aftermarket S300 turbos which utilize the stock cast-iron elbow.

Diesel engines, unlike gasoline engines, don't slow down simply by taking your foot off the accelerator; they rely on service and supplemental brakes. An exhaust brake is a form of a supplemental brake, and they work much differently than their conventional counterparts.

Introducing the Pacbrake PRXB

Pacbrake’s flagship product, the PRXB (pressure regulated exhaust brake), is the unquestioned leader in the supplemental brake industry. The patented PRXB design delivers the strongest braking horsepower, greatest speed reductions and shortest stopping distances possible without the use of service brakes. It maintains optimum retarding performance by maximizing the exhaust backpressure throughout the entire RPM range. Unlike a typical exhaust brake, which requires high RPMs to work properly, the PRXB delivers constant exhaust pressure (braking) as early as 1200 RPM through to the maximum allowable RPM.

Controlled by a master ON/OFF switch, Pacbrake’s exhaust brakes provide whisper quiet supplemental braking that allows service brakes to be used much less, ultimately saving you money. They have the ability to be left on all the time, making it ideal for in-city driving or for steep, downhill grades. This product pays for itself as less wear on the brake pads means fewer brake jobs. 

PRXB Exhaust Brakes: Our Kits

Everything Is Included

Here at Pacbrake we like to keep things simple for our customers. From your first one-on-one conversation with our sales experts to the final product, we provide a total package of quality service and parts. There are a number of components required to operate an exhaust brake, but we conveniently include everything you need in our exhaust brake kits. Check out the information below to learn what is included in our kits.


Every exhaust brake requires an air compressor and air tank to operate. Often mounted under the hood, Pacbrake’s air compressor builds up pressure in the air tank that is released during braking.

Pacbrake’s ½ gallon air tank works with the exhaust brake and air compressor to speed up the exhaust brake cylinder activation. It does this by storing air pressure (created by the compressor) and holding it until needed. Outside the air tank there is a 135 PSI pressure switch that controls the amount of air pressure contained inside. As the pressure drops a signal is sent to the compressor to create more air, thereby filling the tank back to its full capacity.

Generally frame mounted, this onboard air tank also provides an air source for operating air horns and air springs (as well as any other air-operated accessories your vehicle may have). PLEASE NOTE: If you are operating more than one air operated product and prefer a larger air tank and/or compressor, upgrades are available.

A 25ft curly hose with an assortment of accessories is also included and easily stored in a heavy duty nylon bag. Just attach the curly hose to the quick disconnect chuck off of the air compressor (your external air source) and you’re able to perform a variety of jobs including:

  • Filling tires and checking air pressure
  • Inflating air mattresses, footballs, beach toys etc.
  • Blowing air (for cleaning, dusting, quick removal of debris)
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