Sounds like U joints. Mine on the rear shaft went out at exactly 100,000 miles, and these ones for whatever reason do not check like other U Joints you may be accustomed to, you really have to get some leverage on them, have a shop check them. $$$ on at least one will be having dried up remains in one of the caps. Been covered here before also. Be sure to get greasable ones, IIRC, Spicer Part # 3-1088. Definitely get checked before you go on trip, they get bad real quick!