Ram’s heavy-duty lineup pairs the brand’s towing and chassis engineering with Cummins inline-six turbo-diesel power for serious work capability. For 2025, Ram has updates to powertrain control and transmissions. Heavy duty Rams feature keep focus on low-rpm torque, exhaust-brake control, and integrated towing tech that makes trailering easier. Let’s take a look at the options.
Since the late 1980s, Ram’s partnership with Cummins has been the blueprint for heavy-duty pickup diesel power: the original 5.9-liter straight-six brought tractor-grade durability and low-rpm torque to Ram HDs, and successive generations—moving from the early 5.9 to today’s 6.7-liter Turbo Diesel—have steadily added refinement, output, and towing confidence without losing that iron-block longevity owners prize. It’s why diesel Rams became favorites with contractors, ranchers, and RV haulers: abundant torque right off idle, strong engine-braking for mountain grades, better efficiency under load than comparable gas engines, and a track record measured in the millions of Cummins-powered Ram trucks on the road. In short, the pairing marries day-in, day-out durability with the kind of relaxed muscle that makes long tows and heavy payloads feel routine. (Cummins)
Ram 2500 Cummins Diesel
The 2500 is the all-arounder: a heavy-duty pickup sized for daily usability yet built to pull and haul with confidence. For 2025, Ram calls out the available High-Output 6.7L Cummins Turbo Diesel I-6 working with a new TorqueFlite HD eight-speed automatic; together they deliver up to 430 hp and as much as 1,075 lb-ft of torque, alongside available grade-assist technology, large infotainment displays, and safety upgrades aimed at long-distance towing. Trim-specific fascias, lighting updates, and expanded driver-information screens modernize the cabin without sacrificing the straightforward work focus Ram HD buyers expect. (Ram 2500)
Ram 3500 Cummins Diesel
Moving up to the 3500 adds serious fifth-wheel and gooseneck intent, plus suspension and axle options tailored for maximum load control. Like the 2500, the 2025 3500 touts the available High-Output 6.7L Cummins paired to the new TorqueFlite HD eight-speed automatic, with Ram listing up to 430 hp and an available 1,075 lb-ft of diesel torque for confident launches, steady climbs, and effective engine-braking on descents. New driver-assistance and infotainment hardware (including an available 14.5-inch touchscreen and Passenger Interactive Display) round out a truck that’s equally at home hauling equipment mid-week and a large fifth-wheel on the weekend. (Ram 3500)
Ram 3500/4500/5500 Chassis Cab
For flatbeds, service bodies, box upfits, and PTO-driven equipment, Ram’s Chassis Cab line brings commercial-grade frames, simplified upfit interfaces, and work-ready wiring and cooling. For 2025, Ram notes a new electronic column shifter and a TorqueFlite HD eight-speed automatic that is standard with the available 6.7L Cummins Turbo Diesel I-6, plus PTO enhancements (including faster remote-throttle response and access from either side) and split-shaft mode for stationary power needs. Offered in 3500, 4500, and 5500 ratings with 4×2 or 4×4, these cabs are built to carry the upfit your business requires while retaining the drivability and service access of the Ram HD platform. (Ram Chassis Cab)
Which truck fits where?
If you’re towing heavy recreational trailers with a daily-driveable footprint, the 2500 strikes a balance of capability and comfort; step to the 3500 for frequent gooseneck/fifth-wheel duty or higher pin weights; choose a Chassis Cab when your payload is an upfit and PTO or stationary power is part of the job. All lean on Cummins’ low-rpm torque and exhaust-brake control to manage grades and loads efficiently while keeping wear and driver fatigue down. (Cummins)