Hey so I just bought a 2002 blazer and it just started to clunk while in 4wd. It only happens when I’m driving and then after the clunk, 4wd disengages. Even after it disengages, it still clunks until I put it into 2wd. It happens in both 4hi and 4lo. It also sometimes starts making a weird humming and rubbing noise when in 4wd. Any help would be appreciated