Your FC40 is basically a Phantom 1 with a different receiver in it (and a wifi camera bolted underneath). So, to use the H3-2D or H3-3D on it you'll need the same modifications a regular P1 would...namely the "P1 upgrade board" or a GCU for the gimbal plus a PMU for the Phantom. The upgrade board is the recommended easier cheaper lighter option, and the latest version even gives you an easy way to plug in a canbus port (for things like iOSD mini etc): http://www.allerc.com/dji-phantom-zenmu ... -8536.html