I would dare say it was the pinion bearing...

Simple test to see which bearing it is:

1. Drive down a road at 60 to 70km/h, a speed at which the noise is fairly noticeable

2. Swerve (safely ) left and right to load up each wheel.

3. The bearing noise will get louder depending on which side the weight of the car is on. ie Left swerve will cause right side to get louder and Right swerve will cause left side to get louder.

If the noise stays the same, I would say it was the pinion bearing.

Or just have someone sit in the middle of the back seat and try and pick the side the noise is coming from. But the above test is more specific.

And if it is a rear wheel bearing, they are closer to $50/$60 per side, plus fitting, as you have found you need special tools to get them off and on.

P.S. do you have superlows or ultralows on the rear end, as that may explain it.

Thanks...I'll try the swerving on the way to work today!

I dont have lows or superlows...stock suspension!

Ok.. So it must be death by natural causes. I thought maybe if you had low suspension the tailshaft or diff flange may be hitting the floor and caused damage to a bearing.