I have been going through multiple pages of diagnosing 4 wheel drive issues and still coming up blank. I was hoping someone can help me... My fuses are good, the lights come on, I can hear the transfer case moving when switching and my vacuum actuator moves freely as it is supposed to.

Now the problem. I switch to 4 high and it will work and stop working randomly, along with some times when it does stop or start working there is a VERY LOUD clunk. Like how something has not broke with as loud and hard is beyond me. Am I looking at the fork issue in the front differential or something else?