I highly recommend you look at the TM and posts that deal with axle seal leaks to understand why it is leaking and where it is leaking from and to.
In short: You would remove the drive flange and pull the drive shaft, then bend lock washer and remove axle nuts (3 inch hex socket needed) and outer seal and wheel bearing. Then pull hub and brake drum as a unit and remove inner wheel bearing and seal.
I have done all seals on mine; With the "experience" of that, if I had a simple leak, I'd now probably pull the shaft and have a good look at where the oil is leaking from. When it has not yet upset the inner wheel bearing and caused the cruddy grease/oil balls to form everywhere, I had good success only removing the outer seal, outer bearing - nothing else - cleaning and repacking same bearing, cleaning and replacing same seal, assembling with correct axle nut torque - and no more leaks. I prefer black RTV in the key way instead of a piece of cork and I also use black RTV instead of the axle flange paper seal. Just saying. There is the "full procedure" to do and there is the abbreviated "fix" that may yield the same result.
If you have never done that job, I recommend you do pull the hub and drum off and check the wheel bearings and brakes while you are at it. Gives you an idea what the rest of the brakes are likely to look like. Wheel bearings like to be wiped clean and re-packed with fresh grease.
If you have access to a pallet jack, you can pull duals, brake drum and hub as one unit, greatly speeding up the process. Always be careful to not scratch the axle stub or damage the bearings.
...for everything cattlerepairman said, except maybe the hex socket......
