I had the same problem out in the trail in my '97 2.5l. It had worked fine other trips but when i put in 4H the transfer case would start grinding in 2nd gear. 4L worked perfect.
I noticed that I had a habit of yanking the shifter into 4H, so by "feeling" the positions of the shifter in different ranges I noticed that when I yanked the shifter I always shifted a little past the engagement point. I tried slowly shifting up from 2H and right when I felt it engage into 4H I stopped. I started driving, 1st gear was good, 2nd was good, and so on
hope this helps