· Please be sure to check your vehicle with OEM OR SIZE carefully before ordering to avoid unusable. · Vehicle compatibility charts are for REFERENCE ONLY. Fit 99-06 Chevy/GMC trucks and SUV (2WD & 4WD) 4.8L, 5.3L, 6.0L. Full length design for power gain from mid to high RPM range. Long transition collector for decreased back pressure. Fully mandrel bent tubes made of 16-gauge 304 stainless steel. Head flanges laser-cut from 3/8-inch thick steel plates. Flanges flattened by hydraulic press for precise and leak-free seal. Flanges chrome plated for corrosion resistance. All joints TIG welded for resistance against cracking and wearing. Polished surface for extra protection against rusting. CNC machine flanges with TIG and MIG welded construction. Engineered and Tested to Exceed Original Equipment Standards and Performance. Header Type: Long Tube. 4.8L, 5.3L, 6.0L V8 Engines Only. · If using a larger 4L80E transmission the bellhousing ears may need to be trimmed for proper clearance. · Earlier 2500’s might have fitment issues due to chassis being designed from previous years. · Earlier years have the upper control arms mounted on top of the chassis, which would cause fitment issues.