Apple PC Compatibility Card 12-inch card - Manual (Page 63)

16 Replace the chassis brace.
Squeeze here, and reinstall the chassis brace. Be sure not to pinch
any of the cables between the chassis brace and the power supply case.
The tab on the chassis brace fits into
a slot in the power supply case.
49 Installing the Card in a Power Macintosh 8500 or 9500