Cummins ISX 3683870 Exhaust Manifold (Rear) PAI 181046CROSS REFERENCE: 3683870 3682549 APPLICATION: Cummins ISX BRAND: PAI 181046 Cummins 3683870 Exhaust Manifold Rear PAI 181046. Diesel performance parts improve exhaust efficiency. Engine replacement ensures stable operation. Designed for durability and long service life. All components are proudly manufactured in the U. S. A. by PAI Industries Inc., an ISO9001 certified company with over 50 years of experience in the heavy duty truck parts industry.