The wiper motor on my 61 has a smaller stroke than my 58tr3.The blades on the 58 travel farther and hit the windshield frame and go too far in the other direction. I have moved them on the splines and still cannot get a nice even pattern like the 61. I always thought they were the same from 57 to 61 until got the 61 going, so are there different configurations or is the stroke adjustable other than the off return setting?