Gen 4 Transfer Box Rear Output Oil Leak

After 37,000 miles of gentle motoring the rear output oil seal on my Gen 4 Jimny transfer box has a slight leak. I only noticed this when I got under the vehicle to check that the dealer had replaced the fuel tank properly after the recent fuel pump recall. That may be a coincidence, although it looks as if the rear prop shaft needs to be moved to drop the fuel tank, so maybe someone has been heavy-handed there.
It isn't a big deal to replace the seal but I have a couple of questions. Is the nut holding the flange onto the output shaft peened on? If so, I would normally replace it, so can the dealer supply this? What do other readers use to tap the seal safely into place? Can Martin Lines supply the seal and the nut through The Big Jimny Store?
My vehicle is 4.5 years old and outside the warranty, so there's no point in mentioning this issue to the dealer unless someone is aware of this being a recurrent problem or subject to a technical notice.
Thanks for any help that can be provided.

Hi

The flange would not have to be loosened or removed to remove the drive shaft so that should not affect the seal. Most likely gravel and mud would shorten the seal life.

I have never had to change these nuts as long as the collar on the nut is not damaged, wich it usually is not. Easiest to use an impact wrench to remove the nut after carefully knocking out the bump on the collar. Then remove the seal without damaging the seat for the seal in the gear box.

I have been using a socket or something with a proper diameter to knock the new seal in place.

Inspect the sleeve on the flange inserting into the seal for excessive wear. if there is a large groove in the place for the lip on the seal it may not take long before you have to change it again. Most likely not a problem on such a new car.