You can't use a drop-pitman arm without changing the steering geometry because of the way the pitman arm is oriented. If you install a 'drop' pitman arm, it would also be a longer pitman arm, which would reduce the amount that the front wheels would turn when you turn the steering wheel. I've seen people modify the steering arm on the driver's-side knuckle instead, which can be raised without affecting the steering geometry, but I would be VERY reluctant to do this because of all the extra load put on the hardware and knuckle.