why is it leaking?

so my under carraige has been leaking for about a month now and it getting worse. i don't understand why it is leaking so randomly but today when i was driving it. i looked under the carriage and it was leaking right under form the Transfer Case... light bulb went off.... i just remembered that i put it into 4X4 mode for like 20 mins about when it started to leak. i didn't raped it while i was in it.. but now why is it leaking after i put it into 4x4 then back to 2h?
now i need to take it to a shop but not before i think was happened? seals? crack? gears exploded?
here the carnage on the street.

http://i178.photobucket.com/albums/w275/northendtrooper/07_16_07_1332.jpg
http://www.automotiveforums.com/vbulletin/%5BIMG%5Dhttp://i178.photobucket.com/albums/w275/northendtrooper/07_16_07_1332.jpg%5B/IMG%5D
http://www.automotiveforums.com/vbulletin/%5BIMG%5Dhttp://i178.photobucket.com/albums/w275/northendtrooper/07_16_07_1332.jpg%5B/IMG%5D

oh btw it is a 1989 isuzu Trooper II

vent clogged?



//bc