sorry for the unclear post, what i was saying was that the squeal continues when i brake and also squeals when the car is just coasting, only when I accelerate is when the noise goes away. Which leads be to believe when more weight is applied to the back (thrust of acceleration) it puts pressure of something, don't know what though.
Thanks for the feedback csnow

btw, what does cupping mean? Is it some sort of wear pattern?