First, excessive vibration is the first clue of worn U-joints, slip splines and even out-of-balance components. An excessively vibrating driveshaft can also cause accelerated wear on other drivetrain components, which can lead to additional issues down the road. Second, If the bushing or bearing that supports the drive shaft or the drive shaft U-joints wear out or fail, they can interfere with the unit’s ability to rotate correctly. This may result in unusual rattling, clunking, or even scraping sounds from underneath the vehicle. Brake & Front End: https://www.brakeandfrontend.com/ TrakMotive: https://www.trakmotive.com/