Be careful of the polarity of the plugs before you just plug the servo into the RX. Futaba radio gear is generally different from Airtronics/Sanwa/Jr/Hitec for the wiring. The positve and negative leads are swapped for the Futaba versus that of the Universal or (Hitec/JR/Air) plugs. Also if you do install Futaba Servos and have the correct polarity, you will have to shave a little plastic off the Futaba servo plug to be able to plug the servo into the RX.

Hope this helps.