Quite a few minor updates and enhancements are coming to the Sierra 1500 lineup, starting with a new set of power retractable assist steps that will be standard on the AT4, AT4X, Denali and Denali Ultimate trim levels. An active exhaust system will be available on SLT, AT4, AT4X, Denali and Denali Ultimate trim levels. A pair of new premium aluminum wheels are available to choose from, as well as a pair of new exterior color options – Downpour Metallic and Thunderstorm Gray. In addition, there are some changes to the powertrain options, most notably the inclusion of the 3.0L Duramax engine in the AT4X.