Sometimes you end up with a threaded end, and sometimes you don't. When you don't, Z it. If you have a choice, always pick the one that gives the least play in the servo arm. By that I mean that sometimes the hole in the arm is reamed instead of precisely drilled and the Z is sloppy. Goldberg for one makes a nice keeper that snugs it up and keeps it from popping off, but get it as close as you can. Linkage slop is bad-bad-bad
On bigger models try to stay away from the nylon clevis and use a metal one with a keeper. Hayes makes a nice heavy duty nylon clevis with a steel pin that's OK too. After a few flights, check the linkages and arms for any vibration slop that may develope. OK, let's go flying...