The first generation of the Chevrolet Silverado was introduced in 1999 with the 1500 and 2500 pickup trucks. The "classic" light-duty GMT400 C/K trucks continued in production for that first year alongside the new Silverado model, and the Heavy-Duty GMT400 pickups continued until 2000, with the new GMT800 Silverado HD (Heavy Duty) released in 2001. A refresh for the 2003 models was introduced, bringing slight design changes (noticeable in the front grille and headlights) and an upgrade to the audio and HVAC controls. Released in multiple models and engine configurations, the first generation would continue in production until 2007, with some variants overlapping with the introduction of the 2nd Generation Chevrolet Silverado that year.