The wait is over. General Motors officially unveiled its all-new 8.3L Duramax Turbo-Diesel V8 on September 24, 2026, and the numbers are substantial: 555 horsepower and 1,230 lb-ft of torque. The new diesel will be available in the 2027 Chevrolet Silverado HD and GMC Sierra HD, which are expected to begin arriving at U.S. dealerships in late 2026. But the biggest story may not be the power numbers. This isn't simply another update to the familiar 6.6L Duramax. GM describes th