I was under my truck today and found a problem: The transfer case(NP208 in an '88) is leaking fluid around the rear output. I don't know much about transfer cases as this is my first 4x4, but I am asumming that there is some sort of seal or o-ring just inside the housing. Is this going to be easy to fix or a big pain in the ass? It looks like it has been leaking for some time, how do I check the fluid level and what kind of lube should I use if it's low? I think I might have broke something.