Dell Precision 340 - Manual (Page 15)

5. Press inward on the two tabs on the sides of the drive bay to disengage the drive from the computer.
6. Slide the drive upward and remove it from the computer.
Removable Media Drive Removal
7. If the replacement drive does not have the bracket rails attached, remove the rails from the old drive by removing the two screws that secure each rail
to the drive.
8. Attach the rails to the new drive by aligning the screw holes on the drive with the screw holes on the rails and tightening all four screws.
9. If you are installing a new drive, connect it to the set of rails that are attached to the inside of the cover.
Removable Media Drive Installation
1 audio cable 5 power cable connector
2 removable media drive data cable 6 removable media drive connector (IDE SEC)
3 power cable 7 audio cable connector
4 data cable connector