It’s hard to believe that as we head into 2025, we will soon be celebrating not only the 25^th anniversary of the Chevy Silverado HD pickup, but also the legendary Duramax diesel engine.

2025 Chevrolet Silverado HD Trail Boss front three-quarter view.

It was 1975 Chevrolet first utilized the Silverado name. At the time, Silverado was a trim offered on the company’s C/K-series of pickup trucks. Opting for the Silverado trim brought bright exterior trim pieces, color-matched carpet, an upgraded dashboard with additional gauges, and woodgrain trim throughout.

2001 Chevrolet Silverado HD one-ton pickup with Duramax 6.6L turbo-diesel V-8 engine, rated at 520 lb-ft of torque.

Fast-forward to 1999 and Chevrolet introduced its very first Silverado pickup model with the all-new light-duty Silverado 1500. For the 2001 model year, the company extended the Silverado nameplate to its all-new line of Silverado 2500HD and Silverado 3500HD heavy-duty pickups, which debuted in the summer of 2000.

Through the years, the Chevy Silverado has offered many industry firsts, including being the first full-size pickup to offer four-wheel disc brakes standard. Silverado was also the first to offer a full-size crew cab with four-wheel steering with its Quadrasteer system. It was the first to include a premium audio system, offered the first full-size hybrid pickup, and was the first to offer a suite of comprehensive safety features.

Chevy’s Silverado HD was also the first pickup to offer a common-rail direction-injection heavy-duty diesel engine. It was on December 19, 1999, that General Motors first announced the coming of its all-new Duramax Diesel 6600 engine. These new engines were set to replace the outgoing 6.5-liter Detroit Diesel that the company had been using since 1992. Development of the engine dated back to 1998 (that’s quick!), and it was conceived as a joint venture between General Motors and Isuzu.

The press release at the time stated:

An all-new Duramax Diesel 6600 engine will debut as an optional engine in GM’s 2001 Chevy Silverado and GMC Sierra 2500HD/3500HD pickups, Crew Cabs, Big Dooley and Chassis-Cab models, next year. It is positioned to help GM set new industry standards for diesel power, performance, durability/reliability and quiet operation in the growing heavy-duty (HD) pickup class. The new Duramax 6600 posts noise, vibration, and harshness (NVH) figures more typical of similar-sized gasoline engines. GM’s current benchmark status in full-size pickups, Isuzu’s in diesel engines, Bosch’s in fuel injection and Allison Transmission’s in commercial-duty automatic transmissions all combine to ensure that next year GM’s Duramax Diesel-powered HD pickups will achieve benchmark status in the full-size diesel pickup segment.

While the Duramax diesel engine was revolutionary at the time, there are several features that have continued throughout the engine’s 25-year run. These begin with the engine’s 90-degree V8 design. Displacement has remained the same at 6,599 cubic centimeters, which is equivalent to 6.6-liters or 402.7 cubic inches. Each of the eight cylinders features a bore of 4.06 inches (103mm) and piston stroke of 3.90 inches (90mm). The block is cast iron and heads are aluminum. The upper portion of each cylinder bore is induction hardened. All Duramax engines utilize high-pressure common-rail fuel injection and feature a single turbocharger mounted at the rear of the lifter valley.

While the first 25 years of Silverado and Duramax have been nothing short of legendary, we can’t wait to see what the next quarter-century has in store for the iconic duo.