General Motors has announced it will widen the availability of its StabiliTrak stability enhancement system to all 2003 model year Chevrolet and GMC full-size pickups and sport utility vehicles fitted with the 5.3-liter V8 engine. A more sensitive four-channel system will be available for some combinations of two-wheel drive, 4X4 and all-wheel drive models in place of the two-channel system previously used, according to GM. Since the introduction of StabiliTrak on three 1997 Cadillac models, GM has continued to improve the system and expand it to other model lines, delivering more than 600,000 vehicles to date. The new four-channel system works with the antilock brake and traction control systems to selectively apply any of the four brakes to help the driver deal with potentially dangerous handling situations, such as severe oversteer or understeer, GM said.