Sierra Classic 2500 4WD V8-8.1L (2007)
10. Remove the clip around the engine harness and the oxygen sensor pigtail.
11. Disconnect the connector position assurance (CPA) retainer.
12. Disconnect the oxygen sensor electrical connector.
13. Remove the oxygen sensor.
14. Remove the exhaust manifold pipe nuts.
15. Using the transmission jack, lower the transmission slightly.
16. Remove the exhaust manifold pipe.
17. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.
18. Discard the exhaust manifold pipe seal.
19. If equipped with a 6.0L engine, with regular production option (RPO) Y91, remove the exhaust manifold pipe.
20. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.
21. Discard the exhaust manifold pipe seal.
