History Of The 2003-2007 HD Dodge Rams: Common-Rail Cummins, New Transmissions And A Stronger Frame

• January 5, 2023
• Story By
  Mike McGlothlin

Following the half-ton body style change that took place in 2002, Dodge’s 2500 and 3500 series trucks received a fresh look for 2003—but the new look was only the beginning. The high output 5.9L Cummins option was graced with high-pressure common-rail injection and delivered 555 lb-ft of torque on top of 305 hp. The 345hp 5.7L Hemi V-8 showed up to replace the 305hp 8.0L V-10. And new transmission options, in the form of the 48RE automatic, 545RFE automatic and the G56 manual later on, were released to handle the added power of the fresh engine lineup.

Foundationally, the third-gen heavy-duty Rams received a stronger frame, new axles and larger four-way disc brakes, which were marketed as the longest-lasting brakes in the segment. A true four-door crew cab configuration was finally released, along with a single rear wheel 3500 model and Dodge’s trucks came with a 7-year/70,000-mile limited powertrain warranty. In 2005, Dodge resurrected the Power Wagon name in the form of a Hemi-powered ¾-ton and for ’06 the coveted Mega Cab configuration became available for the first time. Without question, the ’03-’07 Rams were more powerful, capable and appealing than Dodge’s HD trucks had ever been.

Common-Rail 5.9L Cummins

If you were after a Dodge Ram 2500 or 3500 because of the Cummins option (which proved to be the case for more than 75-percent of all buyers), the 5.9L inline-six diesel definitely delivered in 2003. The new high output version of the Cummins featured a high-pressure common-rail injection system, which meant the 5.9L was quieter, cleaner and more powerful than it’d ever been. At its release, the 359 ci common-rail Cummins produced 305 hp at 2,900 rpm and 555 lb-ft of torque at 1,400 rpm. Midway through the ’04 model year, the Cummins “600” entered the picture, its name signifying the fact that it turned out 600 lb-ft of torque (along with 325 hp). In ’05 the 5.9L received another bump in torque, eventually topping out at 610 lb-ft, available at 1,600 rpm.

5.7L Hemi V-8: The 8.0L & 5.9L Magnum Replacement

Already having debuted in the 1500 line a year prior, the 5.7L Hemi V8 showed up in heavy duty Rams beginning in ’03. The 90-degree, overhead valve V8 packed a 345hp punch at 5,400 rpm, 375 lb-ft at 4,200 rpm and would end up replacing both the Magnum 5.9L V-8 and 8.0L V10 gasoline options. It was most commonly mated to Chrysler’s 545RFE five-speed transmission and was billed as being more powerful than GM’s 6.0L V8—a popular V8 option at the time. 2003 would prove the last hurrah for the V10 and, believe it or not, you could get an ’03 Ram HD with the 8.0L tethered to a manual transmission. The combination was rare back then and finding one on the road today is almost unheard of.

A Handful Of Transmission Options

Despite the relatively short production run of the third-generation 5.9L Cummins-powered Rams (’03-‘07), several transmissions came and went. In 2003, the carryover 47RE was employed behind the standard output Cummins (235 hp and 460 lb-ft), along with the five-speed NV4500 manual. Behind the high output Cummins the stronger 48RE four-speed automatic got the call, as well as the NV5600 six-speed manual. The Mercedes-Benz G56 six-speed manual transmission was phased in during the ’05 model year. The automatic behind the Hemi V-8 option was the 545RFE five-speed automatic and, although rare, a five-speed manual could be had with the Hemi, too.

Hydroformed Frame And Brand-New Axles

Chrysler all but got away from stamped steel with the third-gen frame, instead opting for hydroformed rails. This accomplished a number of things, including a reduction in the number of welds, greater impact absorption, a stronger, stiffer frame overall and one that weighed less than traditional stamped steel. On 4x4 models, a coil spring suspension was present up front, along with the Dana 60’s replacement: the AAM 925. In the rear, leaf springs were perched atop an AAM 1150, the Dana 80’s replacement. The burly, full-floating AAM 1150 (similar to the version offered in GM HD’s at the time) boasted an 11.5-inch ring gear and a GAWR of 9,750 pounds.

Better Interiors 

Although Chrysler reinvented the cabin layout of a pickup truck in 1994, the competition had caught up by ’03 and it was definitely time for the automaker to up the ante again. Not only were more upscale materials added to the interior, but so was dual zone air conditioning (Laramie models) and eventually a Quad Cab sunroof option and BlueTooth cell phone technology. Of course, the third-gen Rams marked the first time four full-size doors were available on Quad Cab models. The rear doors opened 85 degrees, making for easy entry into a cabin that offered 121.1 cubic feet of space.

The “Mega Cab”

The launch of the Mega Cab configuration was big news for the ’06 model year. Apparently listening to critics that said its Quad Cabs weren’t roomy enough, Chrysler effectively designed the Cadillac of pickup interiors, complete with rear reclining seats. The Mega Cab offered an additional 22-inches of cab space over Quad Cab models, this having been accomplished by shortening the bed length to 6.25-feet. With the release of the “Mega,” Dodge had effectively gone from offering no true crew cab option (’02 second-gen body) to a crew cab option with more backseat space than any other truck on the market in just four years.

Best-In-Class GCWR (At Least For A Period)

With the Cummins option checked, a properly-spec’d 3500 model ’03 Ram flaunted a maximum gross combined weight rating (GCWR) of 23,000 pounds. That beat GM’s maximum rating of 22,000 pounds and Ford’s best of 20,000 pounds. It would take until 2005 (with the redesign of its Super Duty’s) for Ford to best Ram in the overall GCWR category (by 500 pounds). Payload figures weren’t class-leading for Ram, but they were impressive all the same, with an available maximum of 5,020 pounds in ’04, followed by 5,200 pounds for ’05.

Bringing Back The Power Wagon

By resurrecting the Power Wagon name for the ’05 model year, Chrysler caused a major stir in the truck world—and for good reason. The modern era Power Wagon, which was based on the 2500 platform, was highly capable off the beaten path. This was thanks in large part to its being equipped with electronic lockers front and rear, a 4.56:1 axle ratio and 33-inch all-terrain tires. A 1.4-inch factory lift up front and an inch of added height in the rear, Bilstein monotube gas-charged shocks and an integrated 12,000-pound Warn winch also aided off-road efforts. Yet despite no shortage of press for the Power Wagon—and the seeming eagerness for truck lovers to get their hands on them—less than 6,000 North American versions were built between 2005-2009.