leak in transfer case

I have 180,000 miles on my FJ mostly all highway. My transfer case has been slowly dripping gear oil. I have cleaned it and tried to find it as it looked like it was coming from up high. I then thought it was coming from the input shaft. I dropped it and the case was bone dry so input was not leaking. Anyone one there have this issue ? It didn't seamed to be over filled as i took out 1.25 qts of gear oil.