I don't recognize that axle at all... Is it a Rockwell? What are the modifications? Looks like disc brakes, too?
I do recognize the flipped hub though, and it's obvious that either your outer seal or the cork keyway seal has failed which has allowed gear oil to mix with the hub grease... Which is then leaking past the inner seal which is only designed to hold back grease, not the less viscous grease / oil mixture.
Looks like a bearing service and seal replacement is in your future... One thing to check - make sure that the face of the outer bearing race is smooth. The outer seal rides on this surface and if there is any kind of burr or ding from the installation of the race it will chew up the seal in short order.
Jon