Usually it's spring isolators or bushings that have dried out. Might try lubing them up to see if the noise stops, then you'll find the culprit.

 

I have noticed mine gets really bad squeaks whenever i go on dirt. The dealership has told me its the spring pack that deteriorates and kills itself. It happens every 4k miles on mine. Just like clock work!! Best option would be to lube everything up. There is a thread on here for that.

 

Sway bar bushings need a lil lubrication love on mine bout every 5k.

 

I had the same issue. It turned out to be the sway bar bushing also. Some synthetic silicone/ Teflon grease pumped in between the bushing and the sway bar with a needle (inserted horizontally between the bushing and the shaft) stops it for many miles. I think that when the oil gets changed as it runs down the drip tray some falls on the bushing. It might have deteriorated it over time causing the squeak. I have to grease it every 10,000 miles or so.