For 1990-2009 cars

1. Install a new exhaust manifold gasket.
2. Install the exhaust manifold.
3. Add threadlock GM P/N 12345493 (Canadian P/N 10953488) to the exhaust manifold bolt threads.
4. Install the exhaust manifold bolts.

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.

5. Tighten the exhaust manifold bolts in sequence.

Tighten
Tighten the exhaust manifold bolts in sequence to 20 N·m (15 lb ft). Repeat bolt tightening in sequence 2 additional passes.

6. Install the exhaust manifold heat shield studs, if required.

Tighten
Tighten the exhaust manifold heat shield studs to 10 N·m (89 lb in).

7. Install the exhaust manifold heat shield.
8. Add anti-seize GM P/N 12371386 (Canadian P/N 993128) to the exhaust manifold heat shield nuts.
9. Install the exhaust manifold heat shield nuts.

Tighten
Tighten the exhaust manifold heat shield nuts to 10 N·m (89 lb in).