Sliding Door Latch

Thanks for reaching out to us. I think we may be able to help with this handle set, but before I recommend anything I'd like you to remove the handle from the door and show me a clear picture of the mortise slot. This is the hole where the thumb lever on the handle inserts.

The main issue here is that your mortise lock is not a typical design and no handle set in our inventory is specifically meant to work with this application. That doesn't mean that we don't sell a good replacement option; depending on the design of that slot, we could have several promising alternatives or none. It will depend on what I see.

I'll also need you to tell me the distance between the two screw holes on the handle, center-to-center. I have a feeling it's going to be 3-15/16" but it can't hurt to verify.

Once I those two pieces of information I will be able to tell you whether we sell something that will work for this application.

Thanks for these photos. I agree, the hole spacing is almost certainly 3-15/16". However it appears you also removed the mortise lock; I specifically needed to see the slot in the mortise that takes the thumb lever. 

For now, my top recommendation is the 82-030. This may be our best option but you need to check that slot before you buy anything. The 82-030 thumb lever has a flat tail that is designed to insert into a flat, 45 degree angle slot. If your mortise slot looks any different then our 82-030 will not work for you. Just something to keep in mind as you proceed with this project.