GM Service Manual Online
For 1990-2009 cars only
  1. Remove both of the connectors on the top of the fuel injectors and from the engine harness.
  2. Remove the harness assembly.
  3. Remove the lower case.
  4. Loosen all of the valve adjusters, but do not remove.
  5. Important: Do not remove the rocker arm shaft bracket bolts from the valve rocker arm shaft assembly until the assembly has been removed from the engine.

  6. Loosen the valve rocker arm shaft bolts evenly, starting from the outer bolts moving towards the inner bolts.
  7. Remove the valve rocker arm shaft assembly.