I've never used SCO. Systematic way goes as follows:

What gives the shell command "mount"? That will be some lines with (mountpoint, hardware, options) tupels to you. Have a look at the hardware part. In some way the SCSI ID will be part of device file. Alter that file to match the old drive. Mount it with "mount /dev/olddevice /mnt/dir_for_old_drive" (create dir before, act as root).