RE: Internal setup for AMA 424 racer
Most of all of the tanks in the 424 and 428 airplanes go right in the nose of the plane with a bladder tank from jett.
Most of us put the 3 servos right behind the trailing edge of the wing. Depending on your class and the size of your wallet you can put futaba, hitec, jr or your favorite. Your looking for the 225 225mg hitec's, 5245 digital hitec, 3002 futaba's, 3421 Jr's. It depends on how much consistancy on centering you want. Most of these servos have the same amount of torque but centering is what you are going to pay for. You will also see a slight difference in the speed of the servos. Most people use 3421's and 3002's.
Switches can be put in with the servo tray behind the wing. You can turn them off with a metal wire as long as the piece of the switch it is going into is plastic. Most people use metal on the 424 and 428 and then switch to the string on the 422's.
Let me know if you need an pictures for ideas.