Ford 2003 Mustang Workshop Manual page 1704

8. Remove the exhaust manifold.
1. Remove the nuts.
2. Remove the exhaust manifold.
3. Remove and discard the gasket.
9. Remove the oil level indicator tube.
10. Remove and discard the exhaust manifold gasket.
11. To install, reverse the removal procedure.
Use a new exhaust manifold gasket.