The frame for my little rover was discarded, so I made a replacement.
This one has a slot to retain a 3 cell lipo battery under the thing.
Print this out, I ended up using the small toothed gear in the gearbox, and the front holes closest to the motor.
I am pretty sure it won't be possible to use the large toothed gear without a bit of redesign.
I needed to drill out the holes near the gearbox to accomidate the screws correctly.