If you’re shopping for a heavy-duty American diesel in Australia in 2026, you’re really shopping between three trucks: the RAM 2500, the Chevrolet Silverado 2500HD, and the Ford F-250.
All three are now factory-backed remanufactured RHD conversions, all three sit well above the 3.5-tonne towing ceiling of conventional dual-cab utes, and all three are rated at 4.5 tonnes braked in Australian-delivered form. But they are not the same truck, and the engine under the bonnet is the single biggest reason buyers end up loyal to one badge for life.
Here’s what actually separates them, and what to know about each truck’s aftermarket before you sign the contract.
The Three Engines That Define the Segment
The Australian HD diesel segment is defined entirely by three American-built engines:
- 7L Cummins inline-six — fitted to the RAM 2500 and 3500
- 6L Duramax L5P V8 — fitted to the Chevrolet Silverado 2500HD
- 7L Power Stroke V8 — fitted to the Ford F-250 and F-350
All three produce between 380 and 500 hp from the factory depending on year and trim, and all three carry the 4.5-tonne braked tow rating that most HD buyers actually care about.
RAM 2500 — The Cummins Towing Default
The 6.7L Cummins remains the most established HD diesel in Australia thanks to RAM’s head start through Walkinshaw’s Clayton conversion line. Owners love the inline-six character, the long-stroke torque curve, and the fact that the Cummins has the deepest, longest-running aftermarket of any HD diesel on the planet.
If you plan to tow at the upper end of the rating week in, week out, the Cummins has the easiest path to extra capability. Plug-and-play performance parts for the 6.7L Cummins are widely available, and the global Cummins community means you’ll never run out of knowledge or parts support for the engine.
Chevrolet Silverado HD — The Refined Duramax Option
The Silverado 2500HD, converted locally by GMSV, runs the 6.6L L5P Duramax, which is the most refined engine of the three from an NVH standpoint. The Duramax is a V8 in a segment where the Cummins is an inline-six, and that shows up as smoother cruising and a more car-like driveline feel under load.
The Duramax aftermarket is smaller than the Cummins scene in Australia but growing fast as more L5P trucks arrive on local roads. Owners chasing towing headroom typically start with calibration and exhaust changes; specialist Duramax performance upgrades sourced from US retailers fit Australian-delivered L5P trucks directly, because the engine and emissions hardware are identical to the US-market version.
Ford F-250 — The Newest Power Stroke Arrival
The F-250 is the newest of the three to arrive in volume through factory-backed conversion. The 6.7L Power Stroke V8 is the torque king of the group in its latest tune, and Ford households already running a Ranger or Everest find the badge loyalty an easy sell.
The Power Stroke aftermarket footprint in Australia is the smallest of the three today, but the underlying US scene is vast. Buyers planning a future build can source Powerstroke aftermarket parts from US specialists with confidence that fitment matches the Australian-delivered truck.
The Aftermarket Question That Decides Many Buyers
For a lot of Australian HD buyers, the decision actually comes down to what they plan to do with the truck after delivery, not the spec sheet on day one.
If the answer is “tow a 4.5-tonne van at GCM, twice a month, for the next decade,” you want the engine with the deepest parts ecosystem and the longest mechanical track record — that’s the Cummins. But If the answer is “tow occasionally, daily-drive the rest of the time, keep it close to stock,” the Duramax-powered Silverado HD is hard to fault on refinement. If it’s a Ford household, the Power Stroke has the torque numbers and a fast-growing local conversion scene.
All three engines respond well to the standard performance path: calibration via a quality tuner, free-flowing exhaust hardware, and supporting upgrades to fuel and cooling. US specialists such as EngineGo carry vehicle-specific kits across all three engine families with year/make/model selectors that make sourcing the right parts straightforward, even ordering from Australia.
A note on emissions hardware: Any DPF or EGR removal product sold by US retailers is supplied strictly for off-road, competition or agricultural use. Road-registered vehicles in Australia must retain their factory emissions equipment in compliance with state regulations.
So Which One Should You Buy?
There’s no universal answer, but there is a clean framework:
- Heavy-duty cycle, weekly towing, long-term build plans: RAM 2500 (6.7L Cummins)
- Mixed daily use, occasional towing, refinement first: Silverado 2500HD (6.6L Duramax L5P)
- Brand loyalty to Ford or strong preference for the newest factory torque numbers: F-250 (6.7L Power Stroke)
Whichever badge you choose, you’re buying into one of the deepest, most mature engine ecosystems on the planet. Furthermore, the same US aftermarket that has supported these trucks for two decades is increasingly delivering directly to Australian driveways.