Here is a Lionel-compatible O27 gauge three rail gondola for you to run with your military trains. The neat thing about gondolas is you can put all kinds of cool stuff in them.
Menards has released a series of military O cars. This one is from 2020 and has the number 4349 on the side. There are others out there with different numbers. Build a long train of these and fill them up with toy soldiers, tanks, scrap, ammo, you name it.
CONDITION: C-8 like new. No box.