Installation Procedure

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Refer to EXHAUST SYSTEM INSPECTION NOTICE in Cautions and Notices.

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.

Fig 1: Installing Exhaust Manifold Pipe (6.6L)
Courtesy of GENERAL MOTORS CORP.
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.

Fig 2: Installing Exhaust Manifold Pipe (6.0L w/RPO Y91)
Courtesy of GENERAL MOTORS CORP.
If equipped with a 6.0, 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.

Fig 3: Installing Exhaust Manifold Pipe (6.0L & 8.1L)
Courtesy of GENERAL MOTORS CORP.
If equipped with the 6.6L engine, install the exhaust muffler nuts until snug.

Fig 4: Installing Exhaust Muffler Nuts (6.6L)
Courtesy of GENERAL MOTORS CORP.

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.
NOTE: Refer to FASTENER NOTICE in Cautions and Notices.
Tighten the exhaust pipe clamp and muffler nuts.
Tighten
- Tighten the clamp to 40 N.m (30 lb ft).
- Tighten the nuts to 40 N.m (30 lb ft).
Fig 5: Sliding Exhaust Pipe Clamp Around Pipe Connection (6.6L)
Courtesy of GENERAL MOTORS CORP.
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.

Fig 6: Installing Exhaust Manifold Pipe Nuts (6.0L & 8.1L)
Courtesy of GENERAL MOTORS CORP.
If equipped with a 6.0, or 8.1L engine, and the exhaust manifold pipe was replaced perform the following:
1. 17.1. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensor.
2. 17.2. Install the old oxygen sensor.
  Tighten
  
  Tighten the sensor to 42 N.m (31 lb ft).
If equipped with a 6.0, or 8.1L engine, and the exhaust manifold pipe was not replaced perform the following:
1. 18.1. Connect the oxygen sensor electrical connector.
2. 18.2. Connect the CPA retainer.
3. 18.3. Install the clip around the engine harness and the oxygen sensor pigtail.
Fig 7: Installing Oxygen Sensor, Connector, CPA Retainer & Clip (6.0L & 8.1L)
Courtesy of GENERAL MOTORS CORP.
If equipped with a 6.0, or 8.1L engine, remove the exhaust muffler. Refer to Muffler Replacement (4.3L, 4.8L, and 5.3L Engines) or Muffler Replacement (6.0L, 6.6L, and 8.1L Engines) .
Install the transmission support crossmember.
Install the transmission support crossmember bolts.
Tighten

Tighten the bolts to 95 N.m (70 lb ft).

Fig 8: Installing Transmission Support Crossmember & Bolts (6.0L, 6.6L & 8.1L)
Courtesy of GENERAL MOTORS CORP.
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.

Fig 9: Installing Transmission Mount To Transmission Support Nuts (6.0L, 6.6L & 8.1L)
Courtesy of GENERAL MOTORS CORP.