RE: Futaba Servo to JR reciever
Assuming of course that the servos have the (J) plug and not the antique (G) plug then the only issue is that little spline tab on the plugs. Carefully remove it with a blade and you possibly may have to champher two corners on the plug body. All wireing polarity is the same and if plugged in backwards its a non issue, just won,t work and will do no damage.
John