Dell Precision 5860 Tower Service Manual page 44

Steps
Slide and insert the 3.5-inch hard-drive assembly into the slot on the hard-drive bracket.
NOTE: Push the hard-drive assembly into the slot until you hear a 'click' sound, which indicates that the assembly is locked
into position.
Next steps
1. Install the side cover.
2. Follow the procedure in
44 Removing and installing components
After working inside your computer.