What I've found with the metal ball joints ('Heim') isn't wear on that specific joint per se, but noise and vibration being carried into the cabin by lack of compliance. When everything is new this isn't as much of an issue as the other rubber in the system is still soft enough to absorb the harmonics. As the rubber in the body mounts, engine mounts, and other suspension components hardens or develop play later in life the noise and vibration becomes worse in the cabin. This is amplified with metal or poly bushings. Not saying this is the case with the Thuren bar specifically, but having upgraded control arm bushings and rear link bushings on other trucks it does happen. And it's annoying. Most people want to improve with 'upgraded' components where just resetting back to zero mile factory rubber would get them what they want.
