weep hole in rear axle
 

91 montero sport. 4X4. The right rear axle has a weep hole which is now weeping fluid out of the face of the axle. Before I disassemble the rear axle, I would like to be prepared with another "whatever" on hand so I can fix what is leaking. Is it the O-ring or the oil seal or something else? Help is needed.

probablya rubber bung