Adding a Speedi-sleeve at the same time as the new seal would be recommended, too.
Drop p/shaft, loosen jesus nut on output flange, remove screws in h/brake drum, remove drum, remove jesus nut and flange, remove both lower bolts for backing plate/drip bracket, prise protective collar off, remove seal.
Insert seal, re-fit collar, re-fit drip brk and tighten both lower bolts (careful, can twist brk easily!), apply ultrablue to flange & insert, apply ultrablue to inside flange and re-fit washer/nut, clean and re-fit h/brake drum and screws, apply h/brake and tension jesus nut, re-fit rear p/shaft, top up t/case oil, and roady!
sumting like that.....
