- If equipped with a 6.6L engine, install the exhaust manifold pipe.
 
- Apply water based lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
 
- Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.
 
- If equipped with a 6.0L engine, with RPO Y91, install a new exhaust manifold pipe
seal to the exhaust manifold pipe.
 
- Install the exhaust manifold pipe.
 
- Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
 
- Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.
 
- If equipped with a 6.0L or 8.1L engine, install a new exhaust manifold pipe seal to the exhaust manifold pipe.
 
- Install the exhaust manifold pipe.
 
- Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
 
- Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.
 
- If equipped with the 6.6L engine, install the exhaust muffler nuts until snug.
 
Notice: Refer to Fastener Notice in the Preface section.
Important: Ensure that the manifold pipe is square to the exhaust pipe adapter.
- If equipped with a 6.6L engine, slide the exhaust pipe clamp down and around the pipe connection.
 
- Tighten the exhaust pipe clamp and muffler nuts.
 
Tighten
|     •  | Tighten the clamp to 15 N·m (11 lb ft). | 
 
|     •  | Tighten the nuts to 40 N·m (30 lb ft). | 
 
- If equipped with a 6.0L or 8.1L engine, install the exhaust manifold pipe nuts. 
 
Tighten
Tighten the nuts to 50 N·m (39 lb ft).
- Using the transmission jack, raise the transmission.
 
- If equipped with a 6.0L or 8.1L engine, and the exhaust manifold pipe was replaced
perform the following:
 
| 17.1.  | Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensor. | 
 
| 17.2.  | Install the old oxygen sensor. | 
 
Tighten
Tighten the sensor to 42 N·m (31 lb ft).
- If equipped with a 6.0L or 8.1L engine, and the exhaust manifold pipe was not replaced perform the following:
 
| 18.1.  | Connect the oxygen sensor electrical connector. | 
 
| 18.2.  | Connect the CPA retainer. | 
 
| 18.3.  | Install the clip around the engine harness and the oxygen sensor pigtail. | 
 
- Install the exhaust pipe/catalytic converter to the vehicle.
 
- Install the exhaust system hangers.
 
- Depending on which side is being replaced, perform one of the following steps:
 
| •  | Install the exhaust muffler nuts. | 
 
Tighten
Tighten the nuts to 40 N·m (30 lb ft).
| •  | Install a NEW exhaust pipe clamp. | 
 
Tighten
Tighten the clamp to 44 N·m (33 lb ft).
- Install the transmission support crossmember.
 
- Install the transmission support crossmember bolts.
 
Tighten
Tighten the bolts to 95 N·m (70 lb ft).
- Lower the transmission onto the transmission support.
 
- Install the transmission mount to transmission support nuts.
 
Tighten
Tighten the bolts to 40 N·m (30 lb ft).
- Remove the support from the transmission.
 
- Lower the vehicle.