Ian
Unless you have proper workshop facilities, ie Hoist, then I would take out the entire motor/gearbox/transfer case assembly before splitting to change a clutch. I have tried different ways with my F75, gearbox/transfer case out from under car- just taking motor out, both are a pain in the back. The gearbox/transfer case is as heavy as sh@@@@t as is the motor (approx 240kg). I needed two men and a jack to get it back in. The other time when I just removed the engine, I spent about 3 hrs getting the input shaft to realign with the spigot bearing. A real pain. As for the gearbox output shaft nut, I had a gearbox "expert" strip mine on reassembly once, which came off during normal operation. This meant another removal. All the work is relatively straight forward. As for capacities. You will need roughly 6 litres of oil to do the gearbox/transfer case/both diffs. Each diff is about 1 litre. Gearbox is about 2.7 litres. Transfer case is about 1.3 litres.
Hope this helps
Good luck
David
Growing old is compulsary, growing up isnt, and
MUD MAKES EXCELLENT TOOTHPASTE