Whichever rod you use, let me throw in one point: For the connectors at the control surfaces: where you exit the fuselage, I suggest using a long threaded rod with the unthreaded part stuck back into the nylon push rod and using the threaded end to attach to both your clevis/ball joint and the inner pushrod. This makes a very stiff pushrod at the exit area. I have seen numerous models with a bendable pushrod in this area. Not a good thing!