History Of The Cummins-Powered Ram (1989-1993)—The Truck With An Unlikely Hero Engine

• December 7, 2022
• Story By
  Mike McGlothlin

In the late 1980s, Chrysler’s heavy-duty pickup truck line was the equivalent of managed decay. The loss of big-block gasoline V-8 options, the discontinuation of crew cab configurations, an exterior that had gone virtually unchanged since 1972 and an aging overall platform painted a picture of a product on life support. Thankfully, a few good men convinced Chrysler’s top brass that a diesel engine option would not only sell, but make the brand competitive again. After securing a contract with Cummins, a global engine supplier that was also dominating the American Class 8 truck scene, a diesel-powered Ram followed soon after.

The public ate them up and a supply-limited 16,750 Cummins-powered Rams were sold for the ’89 model year. Eventually, Chrysler had to stop taking orders for Cummins-equipped trucks until it could re-supply and ramp up production efforts in 1990. But what else was your money buying you when you invested in a 1989-1993 Dodge D/W 250 or 350? We’ll spell it all out below, from axles to transmissions to brakes and suspension. In terms of towing, payload and fuel efficiency these trucks changed the game forever. In the near future, we'll follow up this article with a full examination of the ’94 Ram 2500 and 3500’s—trucks that once again revolutionized the heavy-duty pickup segment.

5.9L Cummins: The Savior Engine

The 5.9L Cummins turbodiesel has been called the engine that saved Dodge trucks. And while that statement may be up for debate as it pertains to half-tons, it’s certainly true for the automaker’s ¾-ton and larger trucks. With instant name recognition, the only turbocharged diesel in its class, the sole direct injection diesel candidate in its class and packing the most torque in the segment (along with offering the most horsepower per cubic inch in a diesel) the Cummins name was a gigantic selling point—even though it was packaged in the same basic chassis Chrysler had been using since 1972. The Cummins diesel option also came with Dodge’s 7-year/100,000-mile warranty. It packed a modest 160 hp at 2,500 rpm, but produced a class-leading 400 lb-ft of torque at 1,700 rpm.

An Antiquated Platform’s Last Ride

Aside from dual rectangular head lights, wrap-around tail lights and those signature squared off body lines, the ’89-’93 trucks were essentially nothing more than facelifted versions of the D-series pickups that arrived in ’72. Despite this, the aging platform was made to work and the carbon steel frame (with seven cross members for structural reinforcement) was up to the task of holding up to the torque of the Cummins. And many forget that Dodge offered an “all-welded” bed floor design on these trucks, where the bed was void of exposed bolts, unlike the competition, where trapped water would often lead to the formation of rust.

Conventional Leaf Spring Suspension

A solid front axle with leaf spring suspension was the order of the day in this era, and Chrysler wasn’t into reinventing the wheel in this department quite yet. Of course, on two-wheel drive D250 and D350 models, independent front suspension was employed. All models utilized leaf spring rear suspension, which came with different spring ratings depending on the specific configuration. On cab-and-chassis trucks, a bigger leaf stack could increase the vehicle’s payload rating as high as 6,270 pounds.

Dana Axles And Front Disc Brakes

Under the rear leaf springs, the ’89-’93 Dodges packed a Dana 70 axle. The Dana 70 boasted a 10.54-inch diameter ring gear and either a 3.55:1 or (less common) 3.07:1 axle ratio when equipped with an automatic transmission, and 4.10:1 with a manual transmission. The Dana 70 also possessed a gross axle weight rating (GAWR) maximum of 5,500 pounds on ¾-ton models and 6,200 pounds on 1-tons. Four-wheel drive models featured a 9.75-inch diameter ring gear Dana 60 and 12.82-inch x 1.25-inch brake discs. Rear drum brakes were employed (12x2.5-inches), with the braking system being vacuum-assist. Starting in 1990, rear wheel anti-lock brakes were implemented as standard equipment.

A Little Transfer Case Love

Transfer cases don’t get nearly the appreciation they deserve. These power-transfer devices are incredibly strong, often surviving the life of a truck that’s eaten through a handful of transmissions. In the first-gen Cummins’ case, 4x4 versions were all treated to an NP205 married to the transmission. The cast-iron, gear-driven transfer case was used extensively in GM’s and is still widely respected in the off-road world today. For diesel-equipped versions of ’89-’93 Dodge trucks, the NP205 benefited from a 29-spline input shaft while gas versions retained the 23-spline shaft that’d been in use since 1980.

Transmission Options

While later years of Cummins-powered Rams called for a de-tuned version of the 5.9L diesel behind the automatic transmission option, this wasn’t the case from ’89-’93. The three-speed TorqueFlite A-727 got the nod from ’89-’91, with the four-speed with overdrive A518 (later renamed the 46RH) taking over midway through the ’91 model year. For ’93, a $375 dealer-installed “super duty” transmission cooler option became available for automatic truck owners, which increased the maximum trailer tow rating from 12,000 pounds GCW to 14,000 pounds GCW. A Getrag G360 manual transmission, coupled with a 13-inch clutch, was also available throughout the first-gen Cummins’ production run.

“The Hardest Working Pickup In America”

Thanks to the addition of the 5.9L Cummins, Dodge was very formidable in the towing segment. In fact, a 1993 standard cab, 4x2 D250 or single rear wheel D350 spec’d with the Cummins, the Getrag manual transmission and a 4.10 axle ratio was given a gross combined weight rating (GCWR) of 17,000 pounds (the 5.9L gasoline version was rated at 13,500 pounds). Max trailer weight checked in at 11,900 pounds. In its outgoing year (‘93), a Cummins-powered Dodge even won the “Tow Vehicle Of The Year” accolade from the late Trailer Boats magazine. Payload ratings were also competitive, with a properly-spec’d two-wheel drive D250 capable of carrying 4,305 pounds and a dual rear wheel D350 capable of hauling 5,480 pounds.

Curb Appeal That Never Fades

Despite all the modern luxuries available in late-model Ram trucks—along with the 1,000 lb-ft powertrains and 40,000-pound GCWR chassis’—first-gen Rams still get the nod from loads of purists. In Chris Ohl’s case, he didn’t even technically start with a first-gen Cummins, but rather transformed this ’82 crew cab into a show-stopping, 5.9L Cummins-powered, gooseneck trailer-toting farm truck. Dodge die-hards will note that the first-gen Cummins was never offered in four-door configurations… The interior of the Chris’s crew cab is graced with leather fourth-gen seats, front and rear, as well as a ’17 model year center console. His D350 is proof that the classic look of the first-gen is still being sought out by truck enthusiasts decades after the last one rolled off the assembly line.