I have a Phantom 2 with H3-2D gimbal and also a F550. I am going to order a H3-3D gimbal and would like to put the H3-2D onto my F550. The GCU that comes with the H3-3D, is that needed when using the gimbal with the Phantom 2? if not could I use the H3-3D GCU with the H3-2D on the F550? or will I have to buy a H3-2D GCU for that?