I have a 91 YJ Renegade with an auto trans. While driving in 2 wheel drive, I have a ticking or clicking noise that seems to be coming from the front of the transfer case that speeds up and slows down with vehicle speed. When I shift into 4x4 the cllicking goes away or changes to a squeak that only increases with vehicle speed and and gets worse with more load. I forgot to mention that I have locked the front axles in full time so the front drive shaft always turns with vehicle movement. Any sugestions?