i have a question about a 1995 blazer 4x4 ?

when you raise the hood on my blazer there is a small round plastic ball bolted to the hood ! it has a vacuum hose going to it and the hose has a tee with another hose going underneath the car ! is that a vacuum ball for the transfer case ? where on the transfer case does the hose go to ? i want to change the hose and the rest of the vacuum hoses ! also where is the vent for the transfer case at ? thanks guys !