Its dry this morning. However, was leaking down from behind the plate under these 3 bolts. Any ideas if its just a seal (which?) Or so.ething more serious? I have never owned a 4x4 and is out of wheel house
brake leaking at disc.

 

Sorry, its only 2 bolts holding the plate.

 

6 bolts actually, those secure the half shaft to the brake rotor/output spindle of the differential. Leaks in this area if its hub/gear oil, it will usually be a seal, the question is which one.

If the oil leak is on the outside of the brake rotor coming from the middle it's likely a star seal.

AM General part # 5939517 for around $1-3. Brown-red or blue in color. It will be listed as oil retaining seal. In my opinion, it's not mission critical if you keep an eye on the fluid level of your differential but it should be replaced.

If it's inside of the brake rotor then the leak can be the output seal which is AMG Part Number: 6009472 for around 7-9$.

The repair can be done leaving the differential in the truck, you'll have to remove the half shafts [6 bolts plus the retainer bolt on the other end in the geared hub], and then the rotors will drop out revealing the output spindle where you have the two seals.

flashoffroad and humvee net go over methods to replace the seals.