The GMT800 Silverado/Sierra 1500 and 2500 (non Heavy Duty) (light pickup trucks) were released in August 1998 as 1999 models. The "classic" light-duty GMT400 C/K trucks were continued in production for that first year alongside the new models, and the Heavy-Duty GMT400 pickups (alongside the GMT400 SUVs) were continued through 2000, with the new GMT800 Silverado/Sierra HD (Heavy Duty) being introduced. A small refresh for 2003 models was introduced in 2002, bringing slight design changes and an upgrade to the audio and HVAC controls. The latter 2006 and 2007 GMT800 production units used the name Classic to denote the difference between the first and second generation trucks