As you may now in the Rc world, the 6 X 4 configurasion, works bad in the sand.
So the original 540 engine, and the gear boks, i didn`t use.
I put the Disrupter planetery case and a truck puller 3 engine, to increase power.
A TLT Tamiya axle. in the front, and a transfer case to get 6 x 6. :-)
like this.
This truck i use to pull my machines with.