Transfer case ??
 

It pulled a new one on me. I was in 4 hi doing fine, then it kicked out. Indicator light went out. I grabbed the lever and applied pressure, and after that, it seemed ok.
This morning, in 2 hi, a really strange u=joint sounding knocking. Did the various start/stop/backup, neutral in the trans and t-case. Off and on, it did it all the way to work. On the way hoem, some 75 miles, not a peep or wiggle.

I got it thawing in the shop and plan on checking the shift lever and bushing. Also note that the front diff and the rear seal on the t-case oily. New seals planned.

Any ideas before I end up either taking it in or taking it apart?

2008 3500 stock 6.7 six speed.

Turned out that ice had built up so much and so hard around the actual T-case lever, it would not fully engage. Melted it all out, had sticks and gravel in it, and seems to be working now. Incidentally, if you check the fluid level, make darn sure you do not over-tighten the fill plug. The oil-change guy at the dealership checked it for me last month. Found that he had stripped the hex. Took it in this morning and got it replaced. No charge, and all other fluids checked and topped off free. One more good treatment from them. Glad I have a good one.