Legance II sliding patio door / Double Mortise locking mechanism won't lock

I closed the door yesterday and a little piece of metal broke off and now I can't lock the door. It was attached to the something in the small little square in the middle between the two clinchers.I understand what it does after messing with it for a while but I think I need to replace the locking box that slides into the door itself . Total length of the piece is 9 in. and is rounded at both ends not square. Width is 11/16 in. The distance between the top and bottom screw holes in the piece is 7 3/4 inches. The distance between the two middle holes is 6 3/8 inches. I am not real tech savoy it took me most of the morning to figure out got to get you a decent picture but I am persistent !! I think the part I need is 82-238 . If you have it and how much it will cost.

Hi Bob I forgot to ask at the time . The door has a lock that works with a key from the outside also . Does that make the installation any more complicated . Is there anything I need to keep in mind when installing the replacement ?
Thank you Bonnie

Just wanted to let you know that I received the 82-238 double mortise yesterday. Put it in this morning and its working like a champ !! Thanks for you assistance in picking the correct part and the fast delivery.
Sincerely Bonnie