A reel gang mower has a row of front reel cutting units and a row of rear reel cutting units that cut an unbroken swath of grass in each pass. Each cutting unit is connected for propulsion to the mower frame by a four-bar linkage having front and rear pivot links that converge towards a focal point that establishes a virtual pull point through which propulsive force acts on the cutting unit. The rear pivot links can attach to the mower frame at a selected one of different attachment points to thereby longitudinally shift the pull point fore-and-aft relative to the center of gravity of the cutting unit, thus changing the fore-and-aft weight distribution. The rear cutting units in the gang can be configured to have a tail heavy weight distribution relative to the front cutting units to help eliminate marking in the overlap areas between the cutting units.