Heavy-duty pickups are tools. And GM treats its heavies like an heirloom hammer, you know, the one that's had 14 new handles and six new heads? Well, the handle was new in 2011, when most of what you can't see was renewed, so this year the head gets a major upgrade. The cab and box hardware of the 2015 Chevrolet Silverado HD and 2015 GMC Sierra HD are basically identical to the light-duty, with unique front-end sheetmetal that differentiates these trucks, between brands and relative to the light duties. The new styling brings improvements in aerodynamics and engine cooling, with engine intake air better isolated from the hot engine compartment. The 1500 bed's upper tie-downs, underrail LED lighting, EZ Lift torsion-spring-assisted tailgate, rear-bumper corner step, and box hand-grip carry over, the steel hoods lose their louver details, and all bumpers are now chrome.

The new cabs feature greater use of high-strength steel, hydraulic mounts better isolate the cab from the noise and vibration of the frame, and the inset, triple-sealed doors and improved sound deadening further reduce cabin noise. The electrical architecture upgrades to the new K2 architecture, bringing big-screen infotainment, MyLink/IntelliLink apps, front and rear park assist, and more. Seat-mounted side airbags and curtain bags are now available even on 1-ton models. The integrated trailer-brake controller is relocated for greater convenience, and the driver is now assisted by hill-start assist, hill descent control, trailer-sway control, and cruise control that integrates grade braking with exhaust braking on diesels.

Power and torque ratings of the base 6.0-liter gasoline, CNG bi-fuel, and 6.6-liter turbodiesel V-8 engines are unchanged (360 hp/380 lb-ft for the gas/CNG, 397/765 for the diesel), but the various minor enhancements somehow allow the engineers to dial max payload up a smidge to 7374 pounds, while max towing is up to 19,700 pounds for a conventional hitch, and 23,200 pounds for fifth-wheel trailering. Please note that these are still mysteriously conceived internal "mine's-bigger" numbers. None of the Big Three has adopted the rigorous new SAE J2807 towing standard, though all are hopeful that Ford will blink first with its new 2015 light-duty lineup. If they do, the others will follow, as the engineers all know the numbers for their trucks, their marketing brethren just won't let them use them.

Look for the new heavies to thunder into dealers during the first quarter of 2014, by which time we hope to have arranged another HD smackdown comparo to test those big-brag numbers.