Doug's Headers D755Y-R 1-3/4" Tri-Y Exhaust Header for Oldsmobile Motor Home 455 73-78 Thick flanges (3/8 inch to 5/8 inch) with no warping CNC mandrel bent tubes for an accurate fit and a better flow Precision formed long transition collectors that reduces backpressure Heavy gauge tubing (16 and 14G) for longer life Header tubes are pre-polished better appearance