The Yamaha XT350 uses the same cable with the same drive and the same threads/diameter as the XJ600 (Seca II). I bought a new one on EBay, made my Motion Pro. It's MotionPro Part Number 05-0104. I paid $20.
Here are some pictures:
The XT350 cable is on top, the Seca II cable is on bottom.

They are identical except that the XT cable is about 2" longer than the Seca II cable.

