This is pretty well covered in the rear axle photo guide
I’ve not had any luck finding the rear axle photo guide.
Can somebody point me in the right direction
We hid it just to confuse people!
It took me a while to find it as well, but here it is.
A quick walkthrough for the job goes something like this.
Replacing the VC unit
1)(IMPORTANT) Please make sure the car is adequately and securely supported & cant slip or fall as you will be working right underneath in the middle and probably using hammers & levers when removing parts, OK!
so raise Car to get complete access to the underside,
1) Remove (or at least loosen) the rear diff FILLER plug!
(this ensures that you can replace the oil you are about to remove)
then remove drain plug & drain the oil from rear diff into a clean container(0.5 of a liter)save the oil as you will be putting it back later! clean & replace the magnetic drain plug (it will probably look like a furry silver christmas tree, this is quite normal)
2) Remove the 4 mountings holding the rear anti roll bar in place remove brake bias spring & remove bar. 1 bolt each on the inners & 2 bolts each on the outers, remove the electric/vacuum connections to the freewheel lock.
3) Remove exhaust (twin box) centre section. thats clamps front & rear & some rubber hangers
4) Remove propshaft rear section. 6 bolts front & 3 bolts rear
5) Remove centre nut from VC unit, (I use a deep socket on an air hammer it flies off then) slide old VC unit off its splined shaft, it may need a tap with a rubber/plastic/copper hammer.
and thats it you are now rebuilding & replacing stuff!
6 Fit new VC unit & follow above instructions in reverse order
Torque figures are
VC centre nut = 45 newton meters
Propshaft/VC unit = 45 newton meters
Propshaft rear to centre section = 40 newton meters
In case you were wondering why you saved the old diff oil to reuse?
Well its because new gearbox/diff oil contains detergents and these can wash away all the sludge & muck that is helping to keep your 20 year old oilseals oiltight!
it happened to me on a Syncro gearbox when I changed the oil, after a week the new oil was p1ssing out the drive flanges & everywhere, but more importantly all over my brand new 1 week old clutch, oops
please make sure that you do put half a liter in though, I suppose a top up of new oil wont harm the seals too much. 
Got the part ok, cheers.
Going to be fitting it today