Ford 2003 Mustang Workshop Manual page 294

Lower the rear end of the driveshaft to clear the rear axle housing. Pull the driveshaft rearward
until the driveshaft slip yoke clears the transmission extension housing.
Place a paint index mark on the driveshaft slip yoke and the transmission output shaft.
Place a commercially available plug in the extension housing to prevent fluid leakage.
5. CAUTION: Install the driveshaft with new bolts. If new bolts are not available, apply
threadlock and sealer to the threads of the original bolts.
CAUTION: Do not allow the slip yoke to bottom on the transmission output shaft.
CAUTION: The driveshaft centering socket yoke fits tightly on the rear axle pinion
flange pilot. To make sure that the yoke seats squarely on the flange, tighten the bolts
evenly in a cross pattern as shown.
NOTE: Clean all foreign material from the yoke areas of the driveshaft.
To install, reverse the removal procedure.