2000 Escalade Chirping

[Valerie]

Hey guys... I'm new to this whole forum thing. I bought a 2000 Escalade a year ago. Shortly after I noticed a chirp when I would take off from a dead stop. It doesn't matter if I gun it or give it a little gas from a rolling start. It sounds like I'm trying to be a hard ass and chirp my tires. It sounds like it's coming from the back and feels like there is a pull/slipping going on. I've had a mechanic that changed my Upper Ball Joints look at it and said he didn't hear/see anything. I've also had Les Schwabs look at it and they couldn't see anything either. I don't think it's the tranny. It shifts fine. Any help or advice is greatly appreciated.