It’s often difficult to pinpoint the source of a noise or vibration in a heavy-duty tractor. Many times, wrong parts get pulled out, only to find there’s nothing wrong with them.
Sometimes, folks will put the truck up on jack stands to try to pinpoint a troublesome noise. Often, this can cause more noise in the drivetrain, as these components are engineered to have a certain load on them from the mass of the truck itself.
Once the truck is jacked up, this load is removed and many parts of the drivetrain will start to make noise, when they are otherwise quiet when the truck is moving.