1999 Isuzu Trooper 4X4 making noise

Hello alfredillo, what a coincedence. I purchased a 1999 Isuzu Trooper four wheel drive 124000 miles today. It was a silent drive. I tried the 4wd and shifted it from 4hi to 4lo while in neutral and at a stop. Everything worked well. After putting it back to 2hi it makes the same sound as you described.

Please let me know if you find out what the issue is and I will do the same and let you know if I find out something.
Thanks. Mwarwick72@hotmail. Com

This morning when I woke up I went outside and saw that fluid leaked out near the front passenger tire. I went to a repair shop today and the guy told me that it was the transfer case. He said that it would probably cost at least $1200 to fix depending on how far he'd have to get into it to find problem. I then called the local Isuzu recycler to price the parts, and the guy told me that he hardly ever sees a transfer case go out on the 99 trooper. I explained to him what had happened, and told him that I never used the 4x4 and he said that it's probably the differential. He said that when you don't use 4wd, the fluid will dry up, and when you finally engage the 4wd, it can crack a seal. Makes sense. I'm going to look into it, and find out how difficult it will be to change it. The guy quoted me like $240 for the whole right differential.