95 ram, t-case clicking during braking

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I have searched a bit for a similar thread and only after coming up empty handed did I post this. I have a 95 ram 4x4 with a standard transmission. coming to a stop, I hear a clicking noise that seems to be coming from the tranny/t-case. I can also feel it through the stick. I crawled underneath to see what I could find out, and found the front driveshaft to make the same sort of clicking noise when I rotated it back and forth. I wanted to check the fluid level, and could not remove the plug, however I didn't have time to fight too much. I later risked it a bit and went on a small off-roading adventure, and the problem does not seem to be evident when the truck is in 4wd. I am trying to probe for ideas on what might cause this, and how much time I have before this becomes a catastophic failure. Let me know what you think, I haven't played around with t-case's too much at all, so I don't know too much about them. Anything you can toss my way would help a lot.