Lock on the sliding door

Hello there!

Thanks for reaching out to us. I'm unsure if the white plate shown here is the faceplate to the mortise lock or the keeper installed in the jamb. Can you confirm that for us? Seeing the plate installed may be helpful. 

Thanks for confirming! Since it's a face plate, I recommend you have a look at the 82-239. Review the specifications and see if they match up with your old lock. 

Alternate image for 82-239