You will likely have to remove the fluid lines, steering shaft and then remove the steering sector from the frame. Then you can use a pitman arm puller and a impact wrench to remove the pitman arm.
If you don't have an impact wrench, sometimes the pitman arm puller can be attached to the pitman arm, tighten the puller bolt to the pitman arm shaft then strike the bolt with a 5 lb. hammer which may be just enough to break the pitman arm loose. Then you can remove the pitman arm with a 1/2" drive ratchet.