It sounds like you have a SCSI ID issue (assuming I've interpreted what you said properly). If that's the case, you can usually fix it by changing 3 jumpers on the back of the hard drive. There is usally a label somewhere on the drive that shows which 3 jumpers are for the SCSI ID. The configuration should look different from all of the other devices on the SCSI bus.

Oh, and how dare you bring the wrath of the SCSI gods down upon us! Now half the members of the forums are going to have to reterminate their SCSI busses.