Are you using the 4wd infrequently…which is usually the biggest problem.
As I mentioned earlier, just because it has more then 60k miles, don’t be afraid to ask for help from the manufacturer. They pay the dealer, the dealer gives nothing away. Unplugging something is not usually going to go UN noticed. I would not count on that. But service may help. I would op for that first. If it does help, use the thing regularly on straight roads if you have to, to warm it up. Both the front diff and transfere case…change the rear too, especially if you have a locker.