Google "Dax Quadra", this was a Sierra 4 x 4 based car.

The problem with the system is that the transfer box on the gearbox for the front prop/differential is on the drivers side of the gearbox and therefore takes up space in the drivers footwell.

There's also a 4 x 4 Locost, try a search on the Locostbuilders forum.

Cheers

Chris