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:
Installation
WARNING: To reduce the risk of serious personal injury, read
and follow all warnings,
cautions and notes at the beginning of the removal procedure.
1. Disconnect the battery ground cable and wait at least one minute. For
additional information,
re ...
Gearshift Rail and Fork
Disassembly and Assembly
1. Disassemble the first/second and third/fourth shift rail as follows:
Rotate the interlock plate until it is opposite of the shift links.
Slide off the third/fourth shift fork and shift link. Separate the link
from the ...
Rocker Arms - Inspection
CAUTION: Do not attempt to true surfaces by grinding. Check the
rocker arm pad, side
rails and seat for excessive wear, cracks, nicks or burrs. Check the rocker
arm seat bolt for
stripped or broken threads. Install new components as ncessary or possible ...
