The driveshaft of your Toyota is the direct link that transfers your engine's power to the rear wheels of the vehicle. The tremendous rotational torque that your engine applies to the driveshaft accentuates any irregularities in the shaft or connecting parts, causing considerable noise. Maintain your driveshaft to avoid serious vehicle damage in the future.
The U-joints on your Toyota's driveshaft are what connect the driveshaft to the transmission and rear axle. The tremendous torque transferred from the engine to the driveshaft puts significant stress on U-joints and, over time, causes significant wear. Worn U-joints cause the driveshaft to whine, vibrate, and completely disconnect from the transmission and rear axle. Replace your Toyota's U-joints to stop driveshaft noise and prevent catastrophic engine failure.
A warped driveshaft on your Toyota will cause significant vibration and noise under the body of your vehicle. You may warp your driveshaft by "bottoming out" in your vehicle or enabling large items, like rocks, to be pinned against your driveshaft. As the driveshaft spins to thousands of revolutions per minute, the warp in the shaft causes unstable rotation and noise. The only solution for a warped driveshaft is complete replacement.
Improper lubrication on the U-joints of your Toyota's driveshaft causes whining and grinding noises under your vehicle. U-joint grease should be liberally applied in the connecting areas around the transmission, and the connecting points in the rear axle. You should lubricate the U-joints immediately if you suspect this to be the problem, because delaying the maintenance could destroy your U-joints and possibly your driveshaft.