In the good old days when I worked for Royal Mail we used to do loads of these when they leaked… Best way is to use a centre punch and mark the shaft, the flange and the nut all in line so that when you reassemble them they go back in exactly the same position. If I remember right we also used to mark the washer as well, although I don’t think that’s as important.
The seal can be prised out with a screw driver.
We also used to rebuild diffs. It was one item that you had to get right and use quite a few special tools to do the job correctly, and have a unit that was quiet and would last. There is a collapsible collar that spaces the bearings on the pinion which you have to crush to get the bearing pre load correct. It takes a hell of a torque to crush it and if you go too far you have to throw the spacer away and start again! The bearing pre load was measured with a weigh on a long bar. There were 2 positions for the weight: one for old and one for new bearings. I can remember that when you fitted new bearings there was so much preload on them it was very difficult to turn the pinion by hand!!
Crown wheel bearing pre load was achieved by spreading the diff casing by using the large threaded bearing retainers on either side, 12 though comes to mind.. Its all coming back to me now….
I think Burtons still sell the seals.
Hope that helps.
back to work - no time to update the web site!!