Hi,
1. Remove the filler plug found about half way (or more) up the gearbox housing. To be sure it's not stuck before you drain.
2. Remove the drain plug found at the bottom of the gearbox housing, (after first placing a washing up bowl or similar below to catch the old oil!).
& drain all the old oil.
3. Replace the drain plug.
4. Put new oil (check spec required for your van) into the filler hole until it starts to dribble out of the hole 'cos it's full up to the level of the hole.
5. Replace the filler plug.
Bob's your uncle.
Simon
Simon
July 2011