What else could this be?!?!

[KiltedBanshees93GT]

I just got my car back today from the shop after paying to have the rear bearings replaced. They had been making a really ugly grinding-grunking sound after the car had been driven a few miles, especially at low speed around corners, along with a low pitched rumbling/whirring at speed while going straight. The grunking almost reminded me of a rubbing sound when cornering.
Anyway, I got the car back today, and it feels much tighter, and the at speed rumbling/whirring is gone, but it is still making the "grunking" during turning, (the slower and or sharper the louder). What the hell else could this be? Is the rear end going to pop? The only other thing I can think of other than the pumpkin getting ready to go would be that the slave cylinders on the rear are leaking. Could the brake fluid getting in the drums cause this noise?
I dont know which way to jump with this. I dont want to drive it until the car craps, but right now shes my main transport. I am planning on doing the rear brakes this weekend, but dont see how that could be the problem, especially considering that coming into my neighborhood, I stayed off the brakes, and the noise continued.
Help! Somebody!

J