Ford 2003 Mustang Workshop Manual page 285

7. To check the engine angle, rotate the driveshaft so that the slip yoke ear is parallel to the floor.
Remove the U-joint snap ring, then install the special tool. Check and record the engine angle
reading.
If the angle is not within specifications, repair or adjust to obtain the correct angles.
Inspect the powertrain/drivetrain mounts or frame rails for wear or damage.