Ford 2003 Mustang Workshop Manual page 2421

9. Clean and inspect the transmission fluid pan, gasket and magnet.
10. Flush the fluid cooler tubes. For additional information, refer to
Backflushing and Cleaning
Installation
1. NOTE: A new torque converter drain plug must be used.
Install the torque converter drain plug.
2. Install the torque converter housing plug.
in this section.
Transmission Fluid Cooler —