I have been using hardware from Don's Hobby in Salina, Ks. These are like Rocket City, except much heavier duty. The screw that goes through the control surface is 8-32. The plastic swivel and clevis are sized for the job. I attach custom threaded 1/8" nickle alloy welding rods threaded to 4-40. I use a 4-40 ball link on the servo end.

Vince