I just found this post. Your P51 and my P51 are similar in regards to servo requirements. Mine has x2 ailerons, x2 flaps, x2 elevator, x1 rudder, x1 throttle, and well x2 for gear. I'm running it from a 6 channel radio. For ailerons since the servos are physically installed reversed from each other a standard servo y-connector works well. However for the flaps, elevator, and gear I needed a reverser. Instead of using the reversing y-connector, I used a Futaba SR-10 servo reverser one for each of the flaps and elevator. And a servo synchronizer for the gear with its own power input. This allowed me to trim each half using only a 6-channel radio. After I finished the installation, I realized how much more simplier this would have been if I had a radio with more channels. But it works and it works well.