Remove the upper outer rail reinforcement in order to replace the wheelhouse assembly. Removal of the upper outer rail reinforcement accesses the welds that secure the strut cap to the cowl plenum.

The left and the right front upper rails are part of the wheelhouse service assembly. If damage is limited to the panels, order the panels and replace the panels individually. The fender mounting holes are predrilled on the upper rails. The fender mounting holes lack the formed areas found on the original rails. Use spacers in order to properly position and fit the fender. Order and replace the front portion of the aprons and the battery tray.

1. Remove all the related panels and the components.
2. Inspect the components for damage.
3. Restore as much of the damage as possible to factory specifications.
4. Remove the following components as necessary:

•	The sealers

•	The sound deadeners

•	The corrosion materials

5. Locate and mark the factory welds.

Important: There are 5 welds that secure the strut cap to the cowl plenum. Drill through only one layer of metal. Do not drill through the cowl plenum when installing the new wheelhouse assembly. Mig plug weld through wheelhouse to cowl plenum.

6. Drill out the factory welds. Note the number of welds for installation of the service asembly.
7. Remove the damaged front wheelhouse assembly.

1. Prepare the mating surfaces.
2. Inspect for the proper fit of the wheelhouse service assembly.
3. On the service assembly, drill 8 mm (5/16 in) plug weld holes, as necessary, in the locations noted from the original assembly.
4. Position the service assembly.
5. Use the body dimensions in order to ensure a proper fit.

Important: In areas damaged beyond recognition, space plug weld holes every 40 mm (1 1/2 in) apart.

6. Plug weld and stitch weld accordingly. Measure the strut cap and the fender mounting locations throughout the installation process to ensure proper fit.
7. Clean the welded surfaces.
8. Prepare the welded surfaces.
9. Prime with a two-part catalyzed primer.

Important: Prior to refinishing, refer to GM 4901MD-99 Refinish Manual for recommended products. Do not combine paint systems. Refer to paint manufacturer's recommendations.

10. Apply sealers and corrosion protection materials, as needed.
11. Reinstall all the related panels and components.