The centre diff in an LT230 is a fairly basic arrangement. It has the high/low gear, 2 roller bearings and inside a bundle of gears.
The official way of splitting all of this is with land rover special tools, however if you have a press and the correct clamps you can push these on/off.
Once you’ve taken the nut off and pulled the bearings off, slide all the gears off and you can open up the diff to get inside. What you can see here is the 4 copper domed washers which need replaced (assuming they’ve not completely disintegrated), and the felt washer on the back of both sun gears (red coloured ring).
Once that’s done and it’s been well lubricated it can be closed up, ensuring the alignment marks on both parts of the houses matches up. The bolts get lightly oiled and then done up to 60Nm in an opposites pattern.