I picked up two additional WD
I started with some scans using Hard Drive Sentinel Professional, so I could scan both disks at once;
Both drives completed with 100% health after around 15 hours.
I decided to shuck the drives since I confirmed they had healthy WD Red Nas drives in them.
Removed all the inteneral to leave just the drive.
Installed the drives into the supermicro caddies;
Because I didn’t want to wipe my existing raid array, I had to just expand my volume, which is fine for the time being since I don’t have all my disks anyways. (6 more to go).