Ford 2003 Mustang Workshop Manual page 2916

21. Install the fifth/sixth and reverse shift rail assembly and align the slots of the shift levers with the
shift interlock plate.
22. Clean the mating surfaces of the transmission main case and the transmission adapter plate.
Apply a bead of silicone rubber to the sealing surface on the transmission adapter plate. Install
the spring and detent ball into the front offset lever, then install the transmission case and the
front offset lever.
Make sure the transmission is in neutral to keep the third/fourth gear shift rail from
engaging.
Compress the front offset lever against the guide plate when installing.
Tighten the bolts in a star pattern.