Patio door

Hey Joe. It looks like the thumb lever is perfectly centered between both mounting holes on that inside pull, is that correct? If so, you could adapt our 82-310 Key Lock to your outside pull; you'd just need to remove that circle punchout hole and cut down the tailpiece to the correct size; the video below shows how to do this for a similar key lock. Alternatively, you could just replace this entire handle set with our 82-030B. This handle set comes with a key lock already built in. It will be have the same 3-15/16" hole spacing as your old handle set, and its compatible with your door's mortise lock (our 82-218). Let me know if you have further questions.