I need the latch mechanism
If your mortise fell inside your door, then odds are you want our 82-218. This is a common issue with this particular mortise, but we have a video that shows you our trick on how to avoid that. I'll share it below.
You may also think this part is too big for your opening during installation, but all you have to do is put in at an angle. It's made to be a tight fit. Just make sure to check our listed measurements before you place an order to ensure that they match the space available. Ours are a little different from yours, but I would recommend double checking to be 100% sure. I feel very confident that the 82-218 is what you want.