An auxiliary drive mounted to a reel mower cutting unit includes a cutting reel shaft rotated by a motor and having a horizontal axis, an auxiliary drive housing positioned adjacent the reel mower cutting unit and pivotable on the axis of the cutting reel shaft, an auxiliary drive input shaft engaged to the cutting reel shaft, and an auxiliary drive output shaft coaxially engaged to an end of an attachment outside the auxiliary drive housing by inserting one of the auxiliary drive output shaft and the attachment end through a collet and tightening a nut over the collet. A transverse pin in one of the output shaft and the attachment end may be engaged by a split end in the other of the output shaft and the attachment end.