To finish removing the agitator, take off your leather belt and slip it under the bottom of the agitator until it is centered below the base. Take both ends of the belt in your hand and pull upward sharply, turning your head to one side to avoide the agitator should it decide to pop up forcefully.
Even if you see the drive block and tube as I have shown you above, you must still own a spanner wrench to remove the tub nut holding the drive block down. This tool is available at the same place you buy the drive tube and block. There are a couple of reference manuals for the Whirlpool top loader here on this website that you can use to read the steps involved in pulling the tub.