Transfer case leak

First hello I`m new to the forums. I have an 88 XJ with a 4.0L engine. I bought this in Feb. of this year to replace a dead 87 nissan pickup. I was changing the oil today and noticed fluid around the rear drive shaft right where it exits the transfer case (New Process 231). What am I in for?

PS. I did check the fluid level in the transfer case and it was barely below the fill port. I decided to change the fluid. so that is done.

Probably a leaky rear seal on the t-case; it's not a difficult job to replace.