Abstract: A reverse drive engaging mechanism for a feeder of an agricultural combine, including a power unit including a drive motor having an output gear drivingly rotatable by the motor about an output axis therethrough, and support structure supporting the power unit and configured to be fixedly mounted proximate to a drive gear of a mechanism to be reversed. The support structure supports the power unit such that when the support structure is mounted the output axis will be substantially parallel to a drive axis about which the drive gear is rotatable, and the support structure allows the power unit to be moved substantially linearly in a transverse direction relative to the axes between a disengaged position wherein the output gear is disengaged from the drive gear, and an engaged position wherein the output gear is engaged with the drive gear.