I have one of these:



As you can see behind the gearbox there is a spot for a third servo, while it is possible to use a 2 channel radio, I'd like to use at least a 3-channel radio with full range 3rd channel control (to go from reverse, Neutral and forward speeds) - at least I think it's able to do so.

Since I'm cheap, I am thinking of picking up a used Futaba 4 channel radio from e-bay complete with 4 servos and all from e-bay. I'm looking at the 4YF or the Conquest 4, could someone enlighten me why this might not be a good idea?

I see that Futaba has a ground-only 4 channel radio, the 4GWD. What are the differences, other than the frequency? Do the sticks' axes correspond to the same channels?

Thanks in advance!