Thank you very much. This information is highly useful,
I made a huge mistake though. After several unsuccessful attempts in contacting G-Tech and after having talked to the Apple customer care number a couple of times, I still had not found a certain answer to my query. With the work pressure building up, I hastily placed an order for the thunderbolt 2 drive on amazon. I wish I had waited a bit more. Since I have unpacked the drive, I dont think it is possible to return it or exchange it with the thunderbolt 3 drive and pay the surplus. But I guess it’s life and hopefully I have learnt my lesson.
Thanks again for your help.