Its main features are as follows:
- 7-wide, compared to the 9390 axle width
- Live axles with suspension
- Portal axles
- HOG (Hand of God) steering
Fire Brigade Version:
- Front PTO with water cannon
- Water tank and pump
And this is what I came out with.
The Unimog is used in rough terrains and with the snorkel it's able to cross small rivers.
A water cannon lets the firemen extinguish the fire from inside the cab.
The roof contains some tools and the "water pump" which is an old Pneumatic Spring Cylinder (5103). Its main advantage over the new pumps (2797c02) is the ability to suck in the water.
A Pneumatic Airtank (67c01) is used to store the water.
The pump can be lifted to be operated easily and is stored when not in use.
The most important part of the pumping mechanism is the Pneumatic Distribution Block 2 x 4 with Non-return Valve (4692). There is the tank insert on the left, pump in the middle and the water outlet on the right.
It's a Fire Truck, so it has to be able to extinguish fire. To proof its ability I made a short video.
More detailed pictures to be found on Brickshelf.
Check if you have all the needed parts to build it yourself using Rebrickable.com 
You can also download the LDD-File directly.
Note:
I used colored round Plates to show you where to connect the Hoses.
LEGO®
Digital Designer lacks in some parts, you have to replace the fake parts of these:
- Pneumatic Spring Cylinder (5103)- Pneumatic Airtank (67c01)
- Pneumatic Distribution Block 2 x 4 with Non-return Valve (4692)
With best regards,
Jan