the ZR2, and for the GMC Sierra, called the AT4X and Denali Ultimate. The refresh also includes a new front-end design, as well as a revised interior. All trucks equipped with front bucket seats receive a new center console-mounted transmission shift lever (trucks equipped with a front bench seat retain the previous column-mounted gear selector lever). The 3.0-liter Duramax turbocharged diesel engine now has expanded availability on more trim levels. The short pickup box option has returned available for the Chevrolet Silverado 1500 and GMC Sierra 1500 Regular Cabs since last offered for the 2018 previous generation, which was previously only available in Mexico and the Middle East and is only available with the W/T and Pro trims of the Silverado and Sierra, respectively (these trims also remain the only trims available in the Regular Cab body style). Base Silverado 1500 WT and Sierra 1500 Pro Regular Cab models now receive standard power windows, door locks and push-button start, although keyless entry remains an extra-cost option. All models from the LT (Silverado) and SLE (Sierra) and above receive a newly standard 13.4-inch touchscreen infotainment system, which includes wireless Apple CarPlay and Android Auto smartphone integration and SiriusXM Satellite Radio with 360L (up-level models also receive connected GPS navigation), while base models retain the previously standard seven-inch touchscreen display. A new Silverado 1500 ZR2 model becomes the most off-road capable model in the lineup, while a new Sierra 1500 Denali Ultimate is now the top-tier trim of the lineup, which also receives a new premium Bose surround sound audio system with an amplifier, subwoofer, and genuine metal speaker grilles. Top-tier Silverado and Sierra models receive the General Motors Super Cruise semi-autonomous driving system, which allows for hands-free driving on most highways, and all models receive more standard safety equipment. The new trim level introduced to this series as ZR2 (Chevrolet) which slots in between High Country (Chevrolet) and LTZ (Chevrolet). GMC models receive a similar, though more upscale, model known as AT4X. The refreshed 2022 Chevrolet Silverado 1500 and GMC Sierra 1500 began shipping to dealerships in the Spring of 2022. Both brands will also sell the outgoing models of both trucks, named the Silverado 1500 LTD and Sierra 1500 Limited respectively, alongside the new models. Only 1500 (half-ton) models of both trucks have been refreshed for 2022, with a refresh of the heavy-duty (2500HD and 3500HD) trucks following in 2024.