[ricm]

the servo cables have 3 wires. In the case of Futaba you have:

red = +ve supply
black = -ve
white = signal from receiver

when everything is plugged in, the red wires all end up being interconnected through the receiver, same for the black wires, so the receiver and servos all share a common power connections. Your receiver will get its power from the MFU through the red and black wire(s) of J4, J5, J6 and/ or J7. The white wire of each of these leads carries the control signal in the opposite direction, from the receiver to the MFU. If you didn't have the MFU, one of your 'servos' would be the ESC so the receiver would get power through the red/ black leads from that instead.

If you have the MFU, don't bother with the steering gate. The MFU default mode de-activates the shifter servo in preference for the horn, and its useful to have the horn function whilst steering also. You just need to remember to de-activate the coupler mode (ie. return to horn mode) after you connect/ disconnect the trailer, then there's no chance of the trail de-coupling anyway. I took my steering gate off after my first run and I've never used it since.

If you contact Futaba directly and ask them really nicely, they should send you a shift gate free of charge.....they sent one to me in Australia from USA at no cost after my original one had dropped off and I lost it ;-) I believe the Tamiya Attack unit uses the same stick bezels as the original Futaba Attack 4VWD radio, so the Futaba shift gate should fit. In any case, it shouldn't cost you anything to try.

If you are still stuck, I have spare Futaba shift and steering gates but it'll cost me $12 to ship them to you.