Ford 2003 Mustang Workshop Manual page 2903

12. WARNING: Make sure protective eye wear is in place.
Clean the housing with solvent and dry with compressed air. Clean and check the sealing
surface for nicks or scratches. Inspect the housing for cracks.
If the housing is cracked, install a new housing. If the sealing surface has nicks or
scratches, use a soft stone or crocus cloth to remove.
13. Using the special tools, install the mainshaft bearing cup.
14. Using a suitable driver, install the extension housing seal.
Install the seal with the drain hole at the six o'clock position.
15. To assemble, reverse the disassembly procedure.