Apple PC Compatibility Card (Installation) - Manual (Page 73)

4 If you removed security screws earlier, reinsert them now.
5 Slip the three hooks at the base of the back panel into the grooves on the
computer case.
6 Swing the back panel up and snap it into place.
Snap the plastic back panel into place.
Slip the three hooks on the back panel
into the grooves in the computer case.
Reinstall security screws here.
73 Installing the PC Compatibility Card in a Modular Desktop Macintosh Computer