Looking for a new snib, I think it is a milgard HA0423WH looking at there manual.
This one broke off in the mortise, still trying to get the broken piece out to confirm overall length.
Bob from SWISCO responded:
May 27, 2020
See our 82-240. This is the type of thumb latch used with these style handle set. Keep in mind the way it broke indicates to me that your mortise lock may need to be replaced as well.