Glad you asked, @bostone133. As long as your current transformer is rated for 16v to 24v of AC power, nothing would have to be changed for the Doorbell 3 or Elite. The Doorbell Pro, however, features a specific setup when it comes to wiring. I’ve attached the manual for this installation for reference on steps and hardware, with the biggest difference being the Chime. I recommend also checking our Chime Compatibility list for the Video Doorbell 3 to ensure the chime kit you are using would work with that model. I hope this helps! 