Welcome to the site.
To know what size of generator you need, we would need to know what type of power requirements you have. What are you running? Are you running the truck as a communications vehicle with actual working radios, or are you running something else? Are you actually running anything, or are you just looking for a static type of display? Are you looking for a generator that two people can pickup and move around, or are you looking for a larger trailer mounted generator?
The military has many different types of generators, and it really depends on your power needs. You can get a small 3000Watt military generator, to the huge 20KWatt generator systems.
Give us more information so that we can make some recommendations. Asking what generator you should have with no information is like me saying "Hi, I have a car and want to upgrade it. What should I do?". It is a very open ended question without more info.
Let us know and we would be happy to help.
