Hi Keith,
The search facility is very good and if you search for “Pinion Seal” you will get a lot of useful responses. Overall the job is not too difficult but you will have to obtain or make a special tool to remove the pinion nut (details in the posts) and also make sure it is tightened to exactly the same point by marking the nut position prior to removal. Some of the posts will talk about trying to measure the torque but this is not necessary if you simply mark the position of the nut with a punch. All details can be found from a search and let us know how you get on and if reading the old posts leaves you with any specific questions.