Sliding door lock replacement.

My lock (the non working one) is the grey/silver tone lock.  The replacement lock from Swisco is the (brass/goldtone one)  You can see the brass/goldtone lock has extra metal as pointed out by my red arrow.  The Swisco lock will not fit in my door and I really need a new lock..one that matches the original grey/silvertone.  Thanks for your help

OMG!  Finally.  I tried and tried and FINALLY it fit.  I used a really thin zip tie cable to secure the lock inside the door so it would not fall and I used masking tape to secure the screws to my drill bit, giving me two free hands to move  the mortise around inside my door.  The mortise lock was the right size but my door was old and a bit warped so that is why I could not get the lock to fit.  But after using the thin zip tie thread through the mortise and the masking tape to the non magnetic screws... IT WORKED...That was a challenge, but success feels really sweet right now. Thanks for your convincing me that your mortise was in fact the right size.