Variable Three Speed

The '72 wiper motors were 3 speed, whereas the '69-71 had a variable speed motor. Both came with the wiring pigtail attached to the motor, but, I'm not sure if you can swap them without modifying something. I'd get the '69-71 variable setup if it were me. That way you should be able to use your existing wiper transmission. You should be able to just plug the wiper pigtail right into your firewall plug too.