Well, wheel bearing on rear is located on edge of axle tube on each corner.
Its a $30 parts, and bearing itself is easy to change.
But to get to wheel bearing is not easy. You'll have to remove:
Wheel
rotor
caliper
Axle
and to remove axle, you'll need to remove C-Clip which is located inside of deffrential.
To get to C-Clip, you'll need to open deffrential cover, drain the stinky oil, remove the throu bolt out of defferential itself
While your at it, if your thinking about doing ring and pinion, this would be a great time to do it. Inspect spider bearing, and bearing race.
But before you jump to conclusion, there are host of other things you can check(cheaply mind you), like
Level of gear lube. many many people check level of their engine oil, coolant level, brake fluid level. Some people check their transmission fluid level. But most never check their defferential oil level. Because there is no easy ways to check. If your gear lube is low, rearend can certainly make noise(While on its way to self distruction).
You can also check U-joint. don't just jack the car up and shake it with your hand.
you can pick out extreamly worn U joint this way, but if only some of needle bearing is going, you'll not going to be able to detect that. take driveshaft out, and physically inspect them.
make sure both lower and upper control arm bushing is in good shape as well. Rubber bushing do rut out over the years.
Also check where upper control arm is attached to the car, called torque box(I think?) its known to crack under hard use with our car.
Good luck
