Abstract: The header of a combine harvester is modified to include an elongated axial flow rotary separator unit having coaxial threshing and separating portions. The unit is interposed in the header between a generally conventional gatherer portion and a feederhouse. The separator axis is transverse of the combine and parallel to the cross auger of the gatherer unit which transfers gathered crop material directly to the receiving portion of the separator rotor. Separated grain and chaff is delivered by the feederhouse to a cleaning shoe carried in the body of the combine. Straw is discharged onto the ground from the downstream end of the separator unit. In one embodiment the combine body is generally conventional except that the removal of the separator unit permits a deeper grain tank for greater grain tank capacity. Alternative embodiments include an articulated configuration for the combine body in which a front bogie supports a forward mounted header and includes an engine and cleaning shoe.