Knew from garage door opener install man that I would need this device to interface with the Homelinks system. Was cheaper to buy online and intall myself. It did take clearing the old Homelinks codes in my vehicle before it worked, but now works very well. A little bummed that they dropped the price $5 after I had already bought it.
GENIE 3850R works very well with my GENIE receiver #315390R2 that I have operating an old Chamberlin opener.
The receiver was not included in the installation instructions but they were the same as the first (A) instructions you sent.
You probably know all this but just in case not I thought I would comment anyway.
Thanks