C 2500 Yukon XL 2WD V8-6.0L VIN U (2001)
9. Reposition the AIR check valve pipe (crossover) hose spring clamps.
10. Remove the AIR check valve pipe (crossover)(1) from both check valves.
Important: Do not remove the check valve from the AIR pipe unless valve replacement is required.
11. Remove the AIR check valve pipe nuts, pipe (with check valve), and gasket from the left exhaust manifold.
12. Remove the exhaust manifold bolts, manifold, and gasket.
13. Discard the gasket.