misterlv

I have a 07 is250 awd. Last year around winter i kept hearing a clicking noise and it goes accordingly with the car if i went faster or slower. Then it disappeared and now its back. I haven't really pinpointed what it is. I jacked up the car and my boots are fine. There is no grease residue sprung around anywhere. It doesn't happen all the time. Has anyone on here experience this same issue that can shed some light on this? thanks in advance