Hello Melvyn,
I know nothing about these trucks. However, you piqued my curiosity and I found a Danish website dedicated to the FWD SU-COE. Here is photograph of an artillery body like you want to copy. Accessed 17th June 2016 from,
http://www.armyvehicles.dk/fwdsucoegt.htm
It is a very rugged looking truck and will certainly turn heads once it is restored. All the best with it
Here is one still earning its living Accessed 17th June 2016 from,
https://www.youtube.com/watch?v=O5eMZkKFvzY
Another one that looks like a breakdown version - viewed briefly Accessed 17th June 2016 from,
https://www.youtube.com/watch?v=LOuAyJrAVws
Kind Regards
Lionel