Thunderbolt 3 support for Precision 3440 SFF?

I ordered this machine before xmas. I just noticed that the website gives the customization option to add "PCIE Thunderbolt 3 Card (Low Profile) [555-BFWU] / G7F13PO".  Does it mean the motherboard already supports TB3? I am hoping to add a TB3 port to be able to use my eGPU box when needed.

However, I can only find this part #555-beoz on dell website (which says compatible with the old 3420 SFF only).

Dell Thunderbolt 3 PCIe card - 2 Type C Ports, 1 DP in Low Profile | Dell Canada

Also, I understand I need a TB3 header on the motherboard to be able to use TB3. It does not appear 3440 SFF motherboard has a TB3 header similar to this on 3420

Dell Precision Tower 3420 Owner's Manual | Dell Canada

Your help is greatly appreciated.