If I recall correctly, back at the ODE launch party, there was an Ogre Museum that included a lot of work-in-progress and never-released prototype pieces. I believe it was stated publicly at the time that the green unit in the back of this pic was intended to be a prototype for either the Golem or Dragon (or perhaps both).
https://s3.amazonaws.com/ksr/assets/...jpg?1382310486
Source:
https://www.dakkadakka.com/dakkaforu...50/444067.page
If you look closely you can see what looks like it might be an infantry hatch between the treads on the side, as was mentioned upthread.