Well, i have a 7500, and for ME to add another HD, i simply slide it in. Mine has 2 internal bays that take any SCSI-2 hard drives. It is Very easy to install, you simply pull the cover off the computer, and then slide the HD in and plug the two plugs in. I have a 7500, not a 7600, but there's a very good chance they are exactly the same. Hope this helps some.
John