2001 durango slt clunking noise

I have a 2001 durango and when in 4wd it makes a loud clunkink noise from the front, cant figure it out because I cant pinpoint if it is coming from the front or the transfercase it seems to switch where it is coming from, has me stumped has anyone else had this problem, or think of what it could be? also in 2wd it makes a faint similar noise u can bearly hear it