OK, I have a GX 345 (2002) so I'm not sure if they are still the same. I too scratched my head trying to figure out the RIO system. Even the service manual is vague about the actual location of the switch. You will need to remove your deck to start. From underneath the tractor you can trace the path of the mechanical linkage from the reverse pedal to where it passes throught the frame. If you look very close you will find the switch (gray) mounted to the linkage. It is difficult to see but it is located underneath the right side foot rest (deck plate) and very close to the frame. There is no way to actually get at the switch without removing the deck plate or taking out the reverse pedal assembly. But alas! There is another way, and I was amazed at how simple it was once I figured the circuit out. When the pedal is depressed, the switch (which is a normally-closed type) comes into contact with a metal stand-off that is mounted to the frame. This causes the switch to be forced open which in turn interrupts the circuit to the PTO enable relay. When the pedal is depressed, the PTO circuit is interrupted unless it is electrically bypassed by first holding out the RIO switch. Holding out the switch is equivalent to putting a jumper around the pedal mounted switch. What I did to disable mine was to simply remove the small metal stand-off so the switch couldn't open when the reverse pedal was depressed. This is a very easy process and takes about 5 minuets to complete. The stand-off is actually a long bolt with a sleeve over it. With this approach, you don't have to be concerned about altering the wiring at all. The original factory wiring will still be in place. You can always re-install the stand-off later if you decide to sell the machine. Good luck. Let us know if this works for you guys.

-- Anonymous, May 29, 2003