Pella sliding patio door latch

The door might be Pella, but this mortise lock is not their hardware (we do see generic hardware being used on Pella doors from time-to-time; that's fortunate for you, because it tends to be a lot less pricey to replace than Pella-exclusive parts!). See our 82-260 Mortise Lock. I think this should match up, but go over the dimensions to confirm.