A material handling system includes storage locations disposed in racks and a track having a vertical section adjacent one of the racks. A plurality of material handling vehicles are provided, each including a horizontal drive for driving the vehicle horizontally, a vertical drive for driving the vehicle vertically, and a mechanism for transferring items onto or off the vehicle. A vehicle accessory has an opening configured to cooperate with the vehicles. A central controller may be programmed to provide control signals to determine whether a mode of operation to perform an inventory management task is a first mode of operation or a second mode of operation. The central controller may then control the operation of one of the vehicles to operate without the vehicle accessory in a first mode or with the accessory in the second mode.