I am using SketchUp, I made this.
Top view- Look good top stud on seat in the mine cart.

Bottom view- awesome look!!! Bottom and top stud under the mine cart.

Joints view - milkshape, the joint attched to the model for driver and wheels. (mount0, hub0 to hub3)

Error View- test this the vehicle and glitch the texture on the vehicle.

I add collision box on the mine cart collision-0, you notice that the top stud on the seat and bottom look like glitch on the model and the wheels are not together attach to mine cart body. what it went something wrong?!?! I hope you guys help with this then I able fix it make better.