AutoTrak transfer case
Every so often, I drive around in Auto4WD. From what I've been told, this gets everything turning, lubricating and building up heat which helps "boil-off" excess moisture in the various components. Every 50K miles, you should change the transfer case fluid, too. Basically, when you're going to be on the highway for a while, throw it either into 4HI or Auto4wd to help keep things lubricated. I use Auto4wd every time it rains because it's fun to see what it takes to get it to kick in.
NOTE: the AutoTrak transfer case uses SPECIAL BLUE FLUID. If you put regular automatic transmission fluid in it, it'll have problems which will surface as a driveline clunk that ALOT of people have problems with.
I had a clunk in my transfer case and found a few different remedies - only to read somewhere that SOME AutoTrak cases were accidentally filled with Automatic Tranny fluid. The fix was to replace the red tranny fluid with the blue stuff: drain red, add blue, drive around for 50 miles, drain, add more blue. My clunk went away - it was like magic, I tell you. Now, it's starting to feel like it's coming back, so it's time to change the fluid again.