Applicable Models - Automotive Headlight Assemblies For GMC Sierra 1500 1999 2000 2001 2002 2003 2004 2005 2006,For Sierra Classic 1500 2007,For Sierra Classic 3500 2007,For Sierra 2500 1999 2000 2001 2002 2003 2004,For Sierra 3500 2001 2002 2003 2004 2005 2006 (Does not fit 1999 Sierra Old Body Style / 2007 Sierra New Body Style models). Easy to Install - As a fully compatible replacement for factory parts, our bolt-on style headlights are designed for quick and easy installation, requiring no modification or drilling. Product Compliance - SCITOO strictly adheres to DOT & SAE safety standards which all OE light manufacturers must abide by. Fully Sealed - With the sealing technology,our headlight assembly are completely sealed to prevent moisture from getting into the housing.with ventilation hole at the back of housing to regulate the headlights temperature to avoid fogging problem and keep the headlights bright and clear to ensure years of use. After Sale - 30 Days Refund & 90 Days Defective Item Replacement Warranty! Any Issues With Your Item Please Email Us and We Will Help You!Please check the "Check Fit" to try if this replacement fits your vehicle, with any question or problem, please feel free to contact with us.