GM Service Manual Online
For 1990-2009 cars only

Transmission Support Replacement 4L80-E 4.3L, 5.7L, 6.5L Diesel

Removal Procedure

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the transmission.

  3. Object Number: 321574  Size: SH
  4. Remove the nut retaining the transmission mount to the transmission support.
  5. Remove the bolts and the nuts retaining the transmission support to the frame.
  6. Raise the rear of the transmission.
  7. Remove the transmission support from the frame.

Installation Procedure


    Object Number: 321574  Size: SH
  1. Install the transmission support to the frame.
  2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the bolts and the nuts in order to retain the transmission support to the frame.
  4. Tighten
    Tighten the nuts to 68 N·m (50 lb ft).

  5. Lower the rear of the transmission.
  6. Install the transmission mount to the transmission support.
  7. Install the nut in order to retain the transmission mount to the transmission support.
  8. Tighten
    Tighten the nut to 50 N·m (37 lb ft).

  9. Remove the safety stands.
  10. Lower the vehicle.

Transmission Support Replacement 4L60-E w/5.0L, 5.7L

Removal Procedure

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the transmission.

  3. Object Number: 321575  Size: SH
  4. Remove the nut retaining the transmission mount to the transmission support.
  5. Remove the bolts and the nuts retaining the transmission support to the frame.
  6. Raise the rear of the transmission.
  7. Remove the transmission support from the frame.

Installation Procedure


    Object Number: 321575  Size: SH
  1. Install the transmission support to the frame.
  2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the bolts and the nuts in order to retain the transmission support to the frame.
  4. Tighten
    Tighten the nuts to 68 N·m (50 lb ft).

  5. Lower the rear of the transmission.
  6. Install the transmission mount to the transmission support.
  7. Install the nut in order to retain the transmission mount to the transmission support.
  8. Tighten
    Tighten the nut to 50 N·m (37 lb ft).

  9. Remove the safety stands.
  10. Lower the vehicle.

Transmission Support Replacement 4L60-E w/4.3L

Removal Procedure

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the transmission.

  3. Object Number: 321576  Size: SH
  4. Remove the nut retaining the transmission mount to the transmission support.
  5. Remove the bolts and the nuts retaining the transmission support to the frame.
  6. Raise the rear of the transmission.
  7. Remove the transmission support from the frame.

Installation Procedure


    Object Number: 321576  Size: SH
  1. Install the transmission support to the frame.
  2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the bolts and the nuts in order to retain the transmission support to the frame.
  4. Tighten
    Tighten the nuts to 68 N·m (50 lb ft).

  5. Lower the rear of the transmission.
  6. Install the transmission mount to the transmission support.
  7. Install the nut in order to retain the transmission mount to the transmission support.
  8. Tighten
    Tighten the nut to 50 N·m (37 lb ft).

  9. Remove the safety stands.
  10. Lower the vehicle.

Transmission Support Replacement Cutaway w/8.1L

Removal Procedure

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the transmission.

  3. Object Number: 321571  Size: SH
  4. Remove the nut retaining the transmission mount to the transmission support.
  5. Remove the bolts and the nuts retaining the transmission support to the frame.
  6. Raise the rear of the transmission.
  7. Remove the transmission support from the frame.

Installation Procedure


    Object Number: 321571  Size: SH
  1. Install the transmission support to the frame.
  2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the bolts and the nuts in order to retain the transmission support to the frame.
  4. Tighten
    Tighten the nuts to 68 N·m (50 lb ft).

  5. Lower the rear of the transmission.
  6. Install the transmission mount to the transmission support.
  7. Install the nut in order to retain the transmission mount to the transmission support.
  8. Tighten
    Tighten the nut to 50 N·m (37 lb ft).

  9. Remove the safety stands.
  10. Lower the vehicle.

Transmission Support Replacement 4L80-E w/8.1L

Removal Procedure


    Object Number: 321573  Size: SH
  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the transmission.
  3. Remove the nut retaining the transmission mount to the transmission support.
  4. Remove the bolts and the nuts retaining the transmission support to the frame.
  5. Raise the rear of the transmission.
  6. Remove the transmission support from the frame.

Installation Procedure


    Object Number: 321573  Size: SH
  1. Install the transmission support to the frame.
  2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the bolts and the nuts in order to retain the transmission support to the frame.
  4. Tighten
    Tighten the nuts to 68 N·m (50 lb ft).

  5. Lower the rear of the transmission.
  6. Install the transmission mount to the transmission support.
  7. Install the nut in order to retain the transmission mount to the transmission support.
  8. Tighten
    Tighten the nut to 50 N·m (37 lb ft).

  9. Remove the safety stands.
  10. Lower the vehicle.