I noticed it yesterday going through the drive-thru. I jacked it up today and put it in gear. It only does it from about 2-4mph. Above that, it stops. It sounds like it is coming from inside the driveshaft. It's not coming from either yoke that I can tell. The u-joints are fine also. It has almost 85k on it. Wondering if anyone alse has ever had this or knows what it might be?