Alan Curtis also did a metal DOD heavy duty flat car to haul the GHQ M1a1's. N Scale Kits is now handling them. Here is an URL: http://www.nscalekits.co.uk/dodx.html
Micro Trains made a couple of military loads. The one that comes to mind is LVTP tanks. I think they also had some covered military loads too.
As many others have said 1/144 offers the broadest options around, if you don't mind the scale off set. I can second Dragon's quality, another good company is Takara World Tank Museum line. https://www.google.com/search?q=wor...vHOqg2QWBroDoCw&ved=0CDoQsAQ&biw=1517&bih=725
When I assembled by small squadron of seaplanes and float planes I used 1/144 simply because it offered me more variety than the one or two 1/160 models around. I did shorten the fuselage on some and trimmed the wings on a few but they came out good enough for me.
