A revised interior graces these full-size trucks this year. A new driver-side airbag and a shift interlock are added in the interest of safety. The latter requires the brake pedal to be depressed before the automatic transmission's gear selector can be shifted out of "park." This reduces the likelihood that the vehicle will move suddenly and unexpectedly when the transmission is taken out of "park." Power mirrors, revised climate controls and cupholders provide a more user-friendly interior environment.Mechanical enhancements include the addition of standard 4-wheel antilock brakes, improvements in the engines and modifications to the heavy-duty 4L80-E. The four-wheel ABS replaces last year's rear-wheel-only antilock system. Various upgrades to the engines are intended to reduce noise, improve durability and/or increase efficiency. The transmission is revised for quicker 1-2 upshifts during full-throttle applications.