4th Place GMC Sierra 2500 HD AT4 6.6L Duramax
What’s New
hough similar to its LTZ-badged cousin, the new GMC Sierra 2500 HD AT4 brings a unique off-road package to the heavy-duty segment. There’s nothing new about the 6.6L Duramax LP5 turbodiesel and its output of 445 horses and 910 lb-ft of torque. The news comes downstream of the engine with the Allison-branded 10L1000 10-speed automatic transmission. As described by the engineers, the new gearbox is built to withstand more power and torque than the engine in front of it can produce, and get it all to the ground effectively. Also new for the heavy-duty segment
