2 speed to 3 speed wiper conversion

I want to change my 71 swinger 2 speed wiper to a 73 3 speed wiper from a 73 dart sport .does anyone have the part # of the clips or arms I need? I've got the switch but I remember reading you have to change you have to change cranks , clips arms or something like that . Thanks Jim
ooops just had to go a few threads up and there it is