It would not work. 
The Gandy has an on/off solenoid to turn flow to the motor on/off. The control valve does control and doesn't turn off during operation.
If it has left and right clutches the GS Dry Rate controller does not have clutch outputs to operate them.
To use a GS Dry Rate controller you would need to change the motor to one with out the on/off valve, change the control valve motor to a Fast valve instead of standard or replace with a PWM valve. And also lock the clutches in the on position.

The other option would be to use a RC2000, Raven Rate Control Module or a Raven ISO product controller.
These have the ability to operate the on/off, clutches, and the correct programming available to operate correctly.