2002 Jaguar X-Type transfer case

Where is the area the noise is coming from? A much more common suspect is a noisy wheel bearing. The best way to identify which one is noisy is to run the car on hoist, then listen next to each one with a stethoscope. You can also raise the tires off the ground, spin a wheel by hand, and feel for the vibration on the coil spring.

If the noise is believed to be in the drive train, you can use a tool called the "Chassis Ear". That's a set of six microphones, a switch box, and headphones. You place the microphones near suspect parts, then switch between them and listen while driving. Many mechanics have never heard of or seen this tool. Suspension and alignment specialists use them to find the sources of squeaks and rattles.