The main thing at work here is that you apparently did NOT set the SCSI address correctly. If it was 10/16/4.0.0 and is NOW 10/16/4.1.0, then you did not set the SCSI address on the new drive to 0, you set to 1. If you want it to be 0, power the drive off, remove it from the enclosure, set the SCSI ID to 0, reinsert, and power on.
If you just want to create your new device files, you can do an 'insf -H 10/16/4.1.0'. However, be aware that you may wind up with /dev/rmt/4m* files since 3m was already used.
The easiest thing to do is probably double check and fix the SCSI ID on the new drive.