Dell OptiPlex 745 User Manual page 102

1 drive panel
2 release tab
3 drive-panel insert
3. Select the drive-panel insert in front of the drive bay that you want to use.
4. Gently press the release tab of the insert to remove it from the drive panel.
1 optical-drive panel insert
2 floppy-drive panel insert
3 holder for shoulder screws
5. Reattach the drive panel to the front of the computer.
The drive panel only fits one way.