Chris, I had a van the same as yours, but it was a long time ago! If memory serves me right the drain plug, was on the bottom of the gearbox, slightly angled towards the front of the van. I seem to remember using an ordinary spark plug spanner to remove it. The filler plug is accessed by removing the nearside front wheel, and is located on the rear edge of the end of the gearbox casing (at about the 4 o'clock position as you look at it). Fill with SAE 75/80 gear oil untill it starts to run out of the filler plug hole. Do NOT overtighten either filler/drain plug or you will strip the aluminium gearbox threads. I bought a £20 Ronseal pressure sprayer from B&Q which I have modified to make filling gearboxes easy. It has a long wand with a trigger on it for reaching into hard-to-reach filler holes.