You can start with a premade cab and modify into a military style body, it is much easier.
**Warning there are a bunch of pictures***
A Tamiya King Hauler cab is a good place to start, they are under $40
Here is one I have in stock form
This started a King Hauler cab then modified into a Mack
Yes this is my truck
This cab is 100% scratch built, my first scratch built cab
This Orange 6x6 I built uses a modified Man TGX cab
An 8x8 Maz 537 I also built a couple years ago
I took a Dickies Unimog single cab and made it a DoKa a few years ago
This was another build I did using a Jeep as a donor
Another Jeep I built
And yet another Jeep build I did a few years ago
Tamiya Clodbuster body modified into a mid 70's Blazer I did maybe 5 years ago
All it takes is some imagination and determination to make something custom.. I don't care to have the same truck 10,000 other people have.
Sorry to take over your thread, I just wanted to show that a little imagination and plastic can build something out of the ordinary.