The Tractor body shape is defined with four dimensions.
The Length and Width define the overall length and width respectively of the body.
The Cab length is the length of the cab itself and defaults to half the overall body length.
The Chassis width is the width of the chassis behind the cab and defaults to one third of the overall body width.
The Front radius is the radius of the front of the body.
The Wing radius is the radius of the two front corners of the body.