| | Squeek
The squeek is usually caused by a bushing worn or the rear shock worn. Its a very common problem and one that can be easily fixed. I replaced mine in less that an hour and that was the 2 of them.
The reason you hear the squeek apparently coming from the back seats is that the noise travels through the chassis of the vehicle as the shocks are bolted to the chassis. Usually the squeek will come when you drive on any uneven surface or bumpy roads etc.
Hope this helps.