Supreme Suspensions - GMC Sierra Heavy Duty Series High-Strength Carbon Steel Shock Extenders Shock Extension Kit (Black) PRO FITMENTS: 2001 - 2010 GMC Sierra 1500HD (2WD 4WD), 2000 - 2010 GMC Sierra 2500HD and GMC Sierra 3500HD (2WD 4WD); 8-lug models only. CONTENTS: 2x High-Strength Carbon Steel Shock Extenders, Hardware, Instructions and Pro Pack. INSTALLATION: Easy 'bolt-on' installation takes between 1 - 2 hours. No special tools are required. TECHNICAL NOTES: Maintains factory ride quality. BENEFITS: Reduces over extending pistons so that your factory shocks can be reused without compromising ride quality.