Hi y'all (practicing my accent). The 'Wolf' is more correctly known as the Defender XD (for extra duty). About 8000 have been sold to the British army to replace old SIII Lightweights and Defender 90 and 110 n/a diesels. The main differences between this vehicle and the 110 300tdi I own are:
Strengthened chassis, especially at the back
Strong hoops which act as a roll-over bar
2 spare wheels can be carried on the side of the vehicle, bolted to the roll-over bar
PVC 'solid' canopy
Strange looking intake in the normal 300tdi position which is supposed to keep water out.
Much strengthened radiator surround.
What looks like a bigger oil cooler
'Wolf wheels': these are 6.5J x 16, made out of 6mm steel and have ventilation holes in. (I have a set of these on my 110). These wheels are incredibly strong, just don't drop one on your foot!
They come in 90" and 110" sizes, light and medium duty. The heavy duty tender (to replace the 101" V8 gun tractor) was won by the Czech Haflinger. Land Rover did not want to tender for that one (knowing they would lose) and it was for only about 400 vehicles anyway.
The latest ambulance is also a 300tdi-engined Defender, this time a 130". The body is by Marshalls of Cambridge.
Note that the British Forces have a 'diesels only' policy and are even developing a diesel motor-bike to make it a clean sweep.