The TT is built much heavier. The rear axle is of the worm and ring desgin, basically a giant steel screw that will turn the large brass ring gear. The wheels in the rear are larger, heavier as well. The TT stood for Ton Truck. They also move slower than the car. The front axle, front wheels, engine, radiator, wiring, headlights, and gas tank are the same, the rest is basically different.