I have some of those vehicles. Me and Brandlin threw our money into a pot and got a bunch of components sent to us. Very nice vehicles and very adaptable. Jez at Old Crow will sort something cool out for you, he is a top bloke but be aware that he is insanely busy at the moment (hence the Old Crow site is on a temporary hiatus).
I have an eight wheeler and a six wheeler.
The basic vehicle is a six wheeler.
You can get other bits to extend the chassis or add the 'bendy-coupling'.
There are window/plain side panels and various roof panels to accept different sized turrets (or plain ones that don't have a turret).
The standard Old Crow turrets are compatible with these modular vehicles.