Looks like a SCSI HD to me. Are there a set of resisters underneath on the circuit board next to the 50 pin SCSI connection? Those older drives had resisters for termination so you don't need an external terminator (if they are still installed on the drive).
Find some old mac formatting programs like Micronet 7.x or Lido to format the drive.
Find some old mac formatting programs like Micronet 7.x or Lido to format the drive.