Be sure to watch the video on how to correct your limits if you get them screwed up!! I just made it and it will make life EASY for you!!
https://youtu.be/lrEm1AhopXI
This gear swap video explains and shows a Craftsman/Chamberlain/Liftmaster gear swap start to finish. It's not as hard as you might think...C'mon...give it a try!! The worst that can happen is you end up calling a pro to finish the job, but should you succeed, then you saved a ton of money!!
Part #41C4220A
www.allproqgd.com
http://www.facebook.com/pages/All-Pro-Quality-Garage-Doors-Inc/141046239242976?sk=wall