The steppers have six wires, correct? There will be two phases, you need an ohm meter to find which wires are for which phase. There is a center tap plus each end wire on a coil (3 wires per coil) The two ends will have a higher resistance between them while the center tap should be roughly half the resistance. Find the two end wires, for each phase. Those are the 4 you will connect to the G203V. The center taps are not used with bipolar drives and should be insulated from all other wires.