A slot driven low profile sickle drive has an input rotatable about an upstanding rotational axis and carries an eccentric captured in a slot in one end of a pivot arm pivotable about an upstanding pivotal axis. A power source is connected in rotatably driving relation to the input. The opposite end of the pivot arm connects to a knife assembly of a sickle. The input, eccentric and pivot arm are generally flat, and the power source is vertically coextensive therewith for incorporation in or below the floor of a header of a plant cutting machine. Rotation of the input causes epicyclical orbiting of the eccentric, resulting in sideward pivoting of the opposite end of the pivot arm and sickle knife. A second drive can oppositely drive a second sickle knife, such that opposite forces generated by operation of the drives will be largely canceled.