Transmission fluid leaks when in 4H

[No Pitty]

I have a 2000 Expy with all wheel drive and when I engage 4 wheel drive in high range it pours out tranny fluid but not sure where it is coming from. Last time i ran it through some sugar sand for about 5 min and it lost 2 quarts. It is kinda weird because it does not leak a drop when in AWD or when in 4L, just when I run it in 4H. Not sure where it is coming from but wondered if anyone has ever seen or heard of this problem? Someone had said it is the seal that goes from the transmission into the transfer case and it is the transfer case that is overfilling and leaking, but wouldn't it leak all the time if that was the case? Any help would be appreciated.

 

[99EB4x4]

leak

sounds like a transfer case problem i think the tcase shares the same fluid as the transmission