The manual says:
“Important: Only use WD Caviar® GreenTM hard drive assemblies to replace the drives in your My Book Thunderbolt Duo device enclosure. Using any other hard drive assembly voids the warranty for your My Book Thunderbolt Duo.”
Pretty sure mine is out of warranty. In any case, it appears Caviar Green drives are no longer and have been replaced by Blue?
I was considering using the WD Re Datacenter Capacity HDD Model: WD4001FYYG
Has WD provided any formal guidance as to what can be used in the Thunderbolt Duo now that Green is no longer?