Ford Mustang (1999-2004) Service Manual: Chuckle
Chuckle that occurs on the coast driving phase is usually caused by excessive clearance between the differential gear hub and the differential case bore.
Damage to a gear tooth on the coast side can cause a noise identical to a chuckle. A very small tooth nick or ridge on the edge of a tooth can cause the noise.
Clean the gear tooth nick or ridge with a small grinding wheel. If the damaged area is larger than 3.2 mm (1/8 inch), install a new gearset.
To check the ring gear and pinion, remove as much lubricant as possible from the gears with clean solvent. Wipe the gears dry or blow them dry with compressed air. Look for scored or damaged teeth.
Also look for cracks or other damage.
If either gear is scored or damaged badly, install a new ring gear and pinion.

If metal has broken loose, the axle housing must be cleaned to remove particles that will cause damage. At this time, any other new parts in the axle housing must also be installed, if necessary.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle. It is usually
caused by worn/damaged
pinion bearings, which are operating at driveshaft speed. Bearing noise occurs
at all driving speeds. ...
Knock
Knock, which can occur on all driving phases, has several causes including
damaged teeth or gearset.
In most cases, one of the following conditions will occur:
1. A gear tooth damaged on the drive s ...
Other materials:
Removal
WARNING: Always wear safety glasses when repairing an air bag
supplemental restraint
system (SRS) vehicle and when handling an air bag module. This will
reduce the risk of injury
in the event of an accidental deployment.
WARNING: Carry a live air ...
Axle information
Traction-Lokâ„¢ Axle (If Equipped)
This axle provides added traction on slippery surfaces, particularly when
one wheel is on a poor traction surface. Under normal conditions, the
Traction-Lokâ„¢ axle functions like a standard rear axle.
Extended use of other ...
Powertrain/Drivetrain Mount Neutralizing
WARNING: The electrical power to the air suspension system must be shut
off prior to
hoisting, jacking or towing an air suspension vehicle. This can be accomplished
by turning off
the air suspension switch. Failure to do so can result in unexpected inflation ...
