The answer is: color wheel

stop trying to get the arnsew for the hornby comitition like this, its cheatsing.

The Union Pacific "big boy" ; 4 wheel lead truck - 8 drive wheels - 8 (more) drive wheels - 4 wheel trailing truck.

Either a transverse engine for front wheel drive cars (and the occasional rear engine, rear wheel drive car), or a longitudinal engine for front/mid-engine, rear wheel drive cars.

You will need to change the gearbox, swing arm, back wheel and, probably, brake arrangement and shocks.