As the title says, I have a loud squeaking coming from front suspension of my 300E that comes and goes (sometimes there's no squeaking, and then it will suddenly be really bad). When the squeaking is happening, it is pretty loud and can be heard even with the windows up, it squeaks when the front suspension goes up and down (when driving or while pushing up and down on the front of the car at rest) and also when the wheel is turned side to side (even while car is stationary). I have done some searches and see this could be worn ball joints. Any other ideas to check?

__________________
2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car