I need a replacement for the attached lock from a sliding door.

Thanks for posting! This mortise lock appears to be missing its faceplate. Are you able to find that piece? This is also important for how it installs on the door. 

Please let me know if you have any questions.

The mortise lock can be replaced with the 82-265 Multi-Point Mortise Lock. This lock may not be compatible with your existing keeper, so you may also need the 82-249 (which is similar to what you have).

Carefully review and compare the specifications below.

Alternate image for 82-265

Alternate image for 82-249