Looking for 6 5/8" sliding patio door keyed lock handle (be able to lock/unlock door from outside)

Thanks for reaching out to us. We appreciate your patience during this busy season.

This is a very old door. We don't have a lot of information on it, but I can tell you that's no longer made and that you probably won't find any replacement parts for it on the market. In addition to that, Pella hardware is notoriously expensive even when they're easy to get a hold of. If you do find hardware for this door, discontinued as it is, I don't think they will have an agreeable price for you.

So let's go back to the matter at hand, which is that you want to install a key lock on the existing hardware. In short, I don't think we have a key lock that will be compatible with your old mortise lock. The only option we have that may work for you is perhaps a surface mount handle set like our 82-005. This has its own self contained mortise that does not depend on any mechanism in the door. Because of this, the 82-005 is very versatile and can work on just about anything. The only caveat is that you have to drill new holes.

You'll also note that it doesn't have a keyed exterior lock. That's where our 82-306 comes into play. This would replace the flat outer pull that comes with the 82-005. The key tail would go through the door and plug into the mortise that comes with the 82-005, allowing it to lock from the outside.

Please review these parts and let me know what you think.

We unfortunately don't sell a replacement for this mortise lock. As mentioned above, the door is very old and none of our products are compatible. I believe Pella discontinued the series entirely and no longer makes hardware for it. I recommend reading my response above to see my suggestions for repairing this door.