If the hard drive cage is in a SPARC M5-32 or early SPARC M6-32 server, see EMS and Hard Drive Cage Compatibility . Be certain that you have the correct replacement.
Caution - Danger of electrocution: AC circuits in the server share current. Remove all sources of AC current from the server.
Note the order of the hard drives. They must be installed in the same order in the replacement cage.