transfer box is by the handbrake drum and gearbox is drivers side of the box there is a big bolt thats the drain and a star key above for the filler/level plug bit of a pain !
To change all my oils in a 1997 110 300tdi CSW....
Main Gearbox (R380) ATF Dexron II 2.67 litres
Transfer Gearbox... Hypoid gear oil EP 80w-90 2.8 litres
Front axle.....Hypoid gear oil EP 80w-90 1.7 litres
Rear axle......Hypoid gear oil EP 80w-90 2.26 litres
Swivel pin housing....Hypoid gear oil EP 80w-90 .35 litres
This is what the manual recommends.......
The slightly later TD5 has an R380 gear box but it has slight alterations and uses MTF94.
Take the filler plugs out first before the drains... just in case the fillers are seized. You will need a filler bottle with a length of as wide as you can get tubing.... they are a tw@t to fill up...... but what a difference to the drive! May as well do the axles while you are there... they are easier