Sliding Door Handle Set

This is pretty unusual. This looks like a handle set with 3-15/16" hole spacing, like our 82-030; but the mortise lock resembles our 82-238, which is used with 4-15/16" handle sets. I've never seen this before. To be safe, can you remove the handle set and show us a good, detailed picture of the thumb latch on its own? Its shape and style, including the tailpiece, will be a clue how to proceed here. Thanks.

This indeed highly irregular. Again, you have a 3-15/16" handle set interfaced with an 82-238 Mortise Lock, which is typically used with 4-15/16" handle sets. What's more, your handle set seems to use the 82-240 latch lever . . . which is supposed to be used with 4-15/16" handle sets! I am forwarding this discussion to one of my senior colleagues who is the utmost expert with this kind of hardware. I'll see if we can find any answers for you. Thanks for bearing with us. 

It does appear that you have two different types of hardware on your door. Very confusing! You show the 82-238 mortise lock. This lock normally goes with a handle set with 4-15/16" hole spacing like the 82-080, which in turn comes with the turn 82-240 turn lever. However in your other photos you show the a handle set similar to the 82-030 with holes centers at 3-15/16". This handle set is supposed to be used with an entirely different style mortise lock! The 82-030 also comes with the 82-106 latch lever, which will not work with the mortise lock in your door. 

My guess would be that someone in the past repaired this door with the wrong hardware. I think your best bet would be to see if you could adapt the 82-080 to your door, though keep in mind this would almost certainly involve drilling new mounting holes to accommodate the 4-15/16" hole spacing. I can't guarantee this will work, but I believe it is the best solution if you are up to the task. You also could contact a local professional for assistance on this.