Introducing the First-Ever 2019 Sierra AT4

Ahead of the New York Auto Show, GMC pulled the curtain off the latest addition to its new 2019 Sierra pickup line -- the AT4. The alphanumeric name denotes Sierra’s off-road-ready package, which features a 2-inch suspension lift, a locking rear differential, skid plates and a set of off-road-tuned Rancho monotube shocks. The First-Ever 2019 Sierra AT4 comes standard with