You need the model number of the G5 to make sure you have the correct tray.
Beware the G5 logic board. While you have it open, look at the board for bulging or leaking capacitors.
The capacitors should be completely FLAT at the top.
Anything other than flat is likely to cause you a world of grief
I just purchased a Mac G5 but it came used, without a hard drive. I have a hard drive, a 1 TB sata drive, but it doesn't have the hardware to slide in/out of the rails...that's what I need to secure the hard drive in the case itself with the four screws into a rail system. what part # is that? or what do I search for in newegg.com or some online store?