Many thanks to you all for your answers. But problem is that national seal 6859S is not correct. I have that seal. To be clear Steering gear is original -64 Dart manual steering. And sorry for talking millimetre measurements, I don't have inch gauges. Outer diameter of seal is 43 mm and housing for seal in steering gear has 39,35 mm diameter. Seal inner diameter is 29,55 mm (not pushed wide very gently measured) and pitman arm shaft diameter is 28,55 mm. See attached pictures.