Ed,
I think that if they have 2 threaded clevis's one on each end, wouldn't one get shorter and the other get longer if the threaded rod rotated, but still retains the same overall distance? Now if they unscrewed entirely, that's a different matter.

Sometimes a Z bend is necessary. Especially when you dont have much room to work with like throttle linkages near the firewall on a 4 stroke. I personnally don't like them as I think some wires are very brittle and it weakends the joint.