Is a 3 speed wiper transmission teh same as a 2 speed?

You need to swap the motor, along with the short arm bolted to the back of the 3 speed motor, and the long piece of linkage between the motor and the drivers side pivot. The pivot to pivot arms are the same. Change all of the bushings while you're at it! The wiring plugs right back up, and you just need to change the switch.