I get it. But the answer to your question, I purchased the truck from a dealer who purchased it from another dealer where the previous owners had traded it in there. But for my kingpins and leaf springs it was a personal mechanic that recommended it, then I took it to the dealer where the mechanics supposedly diagnosed and proceeded with the job. If it didn't need it then we have 2 mechanics that ill advised me. I do believe that it is hard for mechanics to pinpoint vibrations and so what will end up happening is that they throw certain diagnosis in an attempt to fix it when it may not have been the right solution. Lucky for me my rig was under warranty. however, i did lose valuable time, i've learned never to do that again. and so overall I dont know. so, as far as vibrating, it something annoying and luckily for me wasn't really stopping the truck from operating, it is a good running truck but something i addressed from time to time. I've always thought that this might be a characteristic of the emissions, and so just ignored it whenever the vibrating occurred. It was like a woman moody, when it was that time of month I would try to talk to her to calm her down, but she did vibrate and it was annoying.