You'll need to remove the wheel obviously, brake drum, axle, and hub. The hub nut takes a 2-9/16" socket to remove. You'll need a new hub seal obviously, axle seal (it's a stamped metal seal that goes between the axle and hub), and a new retaining tab and hub nut (recommended not to reuse the nut). If you jack the end you're working on up high enough you shouldn't have to replace much or any gear oil. Don't forget to repack the bearings while you've got them out either.