Apple Performa 6400/180 - Manual (Page 113)

Take Apart Rear Panel - 16
Replacement Note:
Two
plastic tabs on the upper
part of the rear panel must
fit into two slots in the rear
chassis. Position the top of
the rear panel over the back
of the chassis and press
downward to insert the tabs
into the slots. Press along
the sides and bottom of the
rear panel to snap it into
place.