Part Notes: Silverado, Sierra; 6.0L; 8 BOX; Without Extended Cab; Without Rear Exit Exhaust; All; 1 TON; Standard Cab; Option 1; Without 9, 900 Gvwr; 4WD; California, Emissions Code NC1, EMIS. Code NC8;Silverado, Sierra; 6.0L; 8 BOX; Without Extended Cab; Without Rear Exit Exhaust; All; 1 TON; Standard Cab; Option 1; Without 9, 900 Gvwr; 4WD; Federal;Silverado, Sierra; 6.0L; 8 BOX; Without Extended Cab; Without Rear Exit Exhaust; All; 1 TON; Standard Cab; Option 3;Silverado, Sierra; 8.1L; 8 BOX; Without Extended Cab; All; 1 TON; 133" Wheelbase; Option 1; Without 9, 900 Gvwr; 4WD; Without SRW; California, Emissions Code NC1, EMIS. Code NC8;Silverado, Sierra; 8.1L; 8 BOX; Without Extended Cab; All; 1 TON; 133" Wheelbase; Option 1; Without 9, 900 Gvwr; 4WD; Without SRW; Federal;Silverado, Sierra; 8.1L; 8 BOX; Without Extended Cab; All; 1 TON; 133" Wheelbase; Option 3