Application Summary: 1999-2006 Chevrolet Silverado 1500 Base LS LT WT SS Hybrid (Rear) (Bed Type: Fleetside); 2001-2006 Chevrolet Silverado 1500 HD Base LS LT (Rear) (Bed Type: Fleetside & Cylinder: 8); 1999-2004 Chevrolet Silverado 2500 Base LS LT (Rear) (Bed Type: Fleetside & Cylinder: 8); 2001-2006 Chevrolet Silverado 2500 HD Base LS LT WT (Rear) (Bed Type: Fleetside & Cylinder: 8); 2001-2006 Chevrolet Silverado 3500 Base LS LT WT (Rear) (Bed Type: Fleetside & Cylinder: 8); 1999-2006 GMC Sierra 1500 Base SL SLT SLE (Rear) (Bed Type: Fleetside & Cylinder: 6, 8); 2001-2006 GMC Sierra 1500 HD SLT SLE (Rear) (Bed Type: Fleetside & Cylinder: 8); 1999-2004 GMC Sierra 2500 SLT SLE (Rear) (Bed Type: Fleetside & Cylinder: 8); 2001-2006 GMC Sierra 2500 HD SLT SLE (Rear) (Bed Type: Fleetside & Cylinder: 8); 2001-2006 GMC Sierra 3500 SLT SLE (Rear) (Bed Type: Fleetside & Cylinder: 8)