Solo: I have seen this done in "Classic Trucks" magazine a year ago. It was a 50's chev truck, the model with the rear corner windows. The builder used 3 donor vehicles. The builder cut the cab behind the doors and grafted a second cab on behind that, including the door opening. He used the rear half of the second door and took a third door and cut it in half from top to bottom using the left side door on the right and vice versa to make the two rear doors generally square when welded to the first. He used the rear half of the door opening from the third cab as a door frame and grafted that on behind the first cab and front of the second from top to bottom to accomodate the newly fabricated rear doors. If you can pull this one off, you have my respect.