Did you put 50psi in your tyre.....The outside of the spare faces down so you can do this with the spare wheel up if you forgot.
If you have an MT75 gearbox with the grid like pattern on it, the fill hole is on the Nearside (passenger) just above halfway up the casing in line with the gearstick.
Can't recall the exact size as I use a drain plug set but the plug has a square hole and you might get away with a 6mm, 7mm or even an 8mm Allen key or a the drive on a 1/4" ratchet might do.
As for the diff fill hole...well mine is Nearside again and faces toward the front of the van this square hole is slightly bigger 9 or 10mm.
You check em both by undoing filler plugs while parked level and if any oil runs out just do them up again their fine. If not fill them with those squeezy long nozzled gear oil bottles till the oil starts to run out the holes
ATF for gearbox and EP90 for diff..If they are both bone dry you might need about 1 and a half litres in each maximum.
Should only take you 20 minutes or so even rolling about in the road.
But well worth doing for the miles you'll clock up.
if you look on the side of the fuel pump that faces the battery (offside) you should see the BOSCH stamped into the flat face of the side. if so then you can use Veg oil neat if neccessary although mine prefers a drop of Diesel with hers..... about 20% to be exact
