Welcome. The leak in the transfer case, is it from the back part of the housing on the passengers side?
TO open the case, remove the speed sensor, then all the bolts. Nest take the large rubber plug out and use a set of flat snap ring pliers to spread the snap ring that holds the rear bearing in place. Once the bearing slides out, separate the case half and remove the rear.
What causes it to leak and will JB weld be ok to use to fix the leak
THe wear clip in the transfer case for the pump breaks and the tabs of the pump wear through the case. I have not tried JB weld, but it is worth a try. There is a new style clip to prevent this issue.