[Jaine Perotti]

Well, I honestly don't have a good guess as to where those second motors are, although if I had to guess I would say that they are stacked on top of one another.
What do you mean when you say "tracks"? Are the second motors necessarily CIMs? Maybe the second set of motors are located underneath the CIMs, but are harder to see because they are a different kind and they are smaller.
I am still not sure about this though, because I do not see any second set of wires going in that direction from the speed controllers, unless the wires are fed underneath somehow and are out of sight.

I have some other questions about this:
How fast is your robot in high gear and low gear?
Do you use a "dog" shifting method or do you actually move the gears? I like the Technokat inspired shifter.

Looks nice and compact. Good job.
-- Jaine

Oh and one other question, although slightly offtopic: what are you using that big pneumatic cylinder for?