transfer case leak on 1997 Mercury Mountaineer

I was told I have transfer case leaks. Is this an easy, inexpensive repair? What does this indicate?

Asked by for the 1997 Mercury Mountaineer
Any time your dealing with the transfer case it can be expensive, but do you see any fluid on the ground? Maybe get another opinion
Sometimes the engines oil drain plug will leak a little and as you drive it will blow back over the drive train and make it look like somethings leaking, maybe just go thru a chevron oil stop periodically and get you oil changed and they will top off all drive train fluids and give you a report of whats leaking or low on fluid
I will receive second opinion most definately. I do not notice any fluid on ground, but I will keep an eye out.