4 wheel drive noise on a 2005 dakota.

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I have a 2005 dodge dakota with the 3.7 and is 4 wheel drive. When I went to use it last, I turned the knob to 4 lock high. The light flickered more than normal and then stayed on. I proceeded to go striaght only, no turning and I heard what sounded like a growling/ clicking noise. There was no clunk or a metal to metal sound, just a growl and clicking. Its fine in 2 wheel drive and there are no apparent leaks. Any thoughts are wlcome. It has 88,000 miles at this time. Thank You!