I had an existing Craftsman door opener in my garage original to the house (20ish years old). When I went to take the old door opener off, I noticed the old mounting bracket and rail lined up to the new opener. I left all the rails / chain in place and just replaced the motor, and can confirm it is compatible. I had to omit the chain spreader, but otherwise it dropped right into place. The existing door sensors also worked with the new unit too.If you're looking to replace your old Craftsman uniSee full review