You will need to take off any attachment that is bolted to the final (drawbar, fast-hitch, cultivators, etc..).
Then the fender comes off, then the seat, battery box, tool box and disconnect the brake rod.
Then wedge the front axle, then jack up the rear end and remove the wheel/tire.
The platform has to be un-bolted from the axle extension and transmission case, but doesn't have to be completely removed from the brake and clutch pedals.
Remove the final first, then the axle extension. You'll have to reposition your jack/cribbing in this phase, so be careful!!
Now you'll have access to the seal. Use a standard seal puller to remove the old one, then install the new one.
Going back together will be in reverse order.
When you get the final and axle extension off, you'll be able to clean out the oil, dirt and mice nests that seem to accumulate in these parts. Also, you'll be able to evaluate the brake and drum for that side.