The all-new 6.6-liter LP5 Duramax turbo-diesel under the Sierra Denali 3500 hood is one of the strongest engines on the road in a heavy-duty pickup, with a factory rating of 445 horsepower (tops ...

New Duramax combined with interior sound suppression 'should put GM's marquee heavy-duty pickup on the radar of anyone who tows big trailers long distances’ PickupTrucks.com The all-new 6.6 ...