Front Axle Rattle? 2001 AWD

I believe I have found the cause for an annoying rattle in my 2001 AWD. Has Anyone had a Drive line Rattle in the AWD I have checked everything underneath and grabbed the drive line and wiggled it it has some play in the turning of the shaft and makes the noise that I hear. This is my first AWD. The sound seems to be getting lounder but is intermittent. Anyone have any suggestions of the fix or more insite on this problem? Could the front Differential be low on OIL? I see no leaks and figure it is a closed loop system. What Kind of Oil does it take? Thanks in advance for any help.:banghead: