You will not find a Thunderbolt 3 for Thunderbolt 2 cable as an adapter is required to connect to older devices.
One of the (major) differences between Thunderbolt 1/2 and Thunderbolt 3 is that Thunderbolt 1/2 required the cable to be active (power required to work) while Thunderbolt 3 can use standard USB Type C Cables (It's Passive) 1 .
With these older Thunderbolt standards, the cable was active, meaning
The cable itself is a device that requires power (as is
Why most Thunderbolt 1 or 2 devices will require an external power
source to work.)
Thunderbolt 3 is backward compatible, but will require an adapter. 2
Is Thunderbolt 3 backward compatible with Thunderbolt and Thunderbolt 2?
Yes, solutions and products built for Thunderbolt and Thunderbolt 2 specifications will work with Thunderbolt 3 via an adapter .
To make your setup, such as StarTech TBT3TBTADAP TB 3 for Legacy TB Adapter.
I personally used this adapter to connect a 201
2 Thunderbolt Technology Frequently Asked Questions