4 Wheel Drive/SUVs: 1999 jeep cherokee

Question
I just purchased a used cheokee, and when I drive it makes a loud constant noise coming from the back of the truck--any ideas?  thanks, Aly

Answer
Aly , if I were to guess , I would have to say it has rear end noise meaning that the bearings inside the rear end are wore out, this is a very common problem with Jeeps, does the noise get louder or go away when you accellarate or let of the gas ? Sorry for the delay I was out of town thanks ADAM