In midyear 2015, Chevrolet and GMC made enhancements to the all-new Silverado 2500HD/3500HD and Sierra 2500HD/3500HD. Some of these enhancements included a new OnStar telematics system with 4G LTE Wi-Fi capabilities, new wheel designs, new exterior paint color options, new exterior tow mirror designs, a USB port added the glove compartment of trucks equipped with a front bench seat, DURALIFE brake rotors, the availability of dual 150 and 220 amp alternators for models equipped with the 6.6L Duramax Turbodiesel V8 engine, an off-road information screen added to the instrument cluster of 4X4 models equipped with the Z/71 or All-Terrain Packages (the latter is a GMC-only option), a Bi-Fi Compressed Natural Gas (CNG) option for models equipped with the 6.0L Vortec gasoline V8 engine, a new All-Terrain Package available on SLE and SLT Double Cab and Crew Cab models (for GMC models only), a standard heavy-duty locking rear axle for all models, and the removal of HD Radio from the "up-level" IO5 and IO6 infotainment systems. A Regular Production Option (RPO) Code of "AVF" in the upper glove compartment distinguishes early-build 2015 models from their 2015.5 successors.