A crop harvesting machine has a mobile frame which includes a main frame portion supporting a harvesting header along a forward side thereof and a mobile auxiliary frame portion supporting the main frame portion in overlying relation and pivotal in relation thereto about a vertical axis. When the machine is in its field operating orientation, the auxiliary frame portion aligns the main frame portion and header in transverse relationship to the forward direction of machine movement. The machine further has an elongated draft member pivotally mounted about a vertical axis at a central location along the main frame portion and extending longitudinally forward over the header to a forward end adapted for securement to a towing tractor. Conversion of the machine to a road transporting orientation involves: first, actuation of controls for elevating the machine with respect to the field and; then, in coordinated fashion, pivoting the auxiliary frame portion and draft member relative to the main frame portion so as to realign the main frame portion and header generally parallel to the draft member and the forward direction and transverse to the auxiliary frame portion.