2011 Chevrolet Silverado Z71, GMC Sierra 2500HD - 3500HD 8lug Leveling Kit by Cognito. Boxed Upper Control Arms, Cognito Exclusive Fox Aluminum Body Monotube Shocks, Pitman and idler arm support kit. Please note. This is a Customer build with a little larger tire & wheel than recommended and requires fender modification. Contact us if you have any question about wheel and tire clearance.