Wiper question

My experience is in 67,68 2 speed and 3 speed wipers. I've deleted the electric wash pump and used the wash function of the switch to create a one pus equals one complete sweep wiper operation. This doesn't work on the later models for several reasons I dont know what year they changed either. If your wiper switch rotates to low speed when pushed to wash or if the wipers will retun to park from mid/ incomplete sweep when turned off, you have the later type wipersl.