squealing noise 04 grand cherokee

i have a squealing noise comming from what i narrowed down to the rear transfer case. its not a grinding noise and the 4x4 system works fine. its not the transfer case itself but where the shaft comes out, maybe a seal? does this part wear heavily as the car has done only 80,000 kms. the only thing i can think of is i went out in the mud and water and 2 weeks later this annoying squeal starts. got rid of it for 1 day by cleaning around the transfer case and shaft, but now it is back? :frown: