Ford 2003 Mustang Workshop Manual page 1447

7. CAUTION: The bolts are different lengths and must be returned to their original
location.
NOTE: RH shown; LH similar.
Remove the bolts and the timing chain guides (6K297).
Installation
1. CAUTION: Timing chain procedures must be followed exactly or damage to the
pistons or valves will result.
Compress the tensioner plunger, using a soft-jawed vise.
2. Install a retaining clip on the tensioner to hold the plunger in during installation.
Remove the tensioner from the vise.