The lever on door lock

Hey there. You should be able to replace that thumb lever with the 82-107. Note that a broken thumb lever can indicate that the mortise lock in the door is broken and should be replaced. You can see if this is the case by attempting to manually 'throw' the lock with a slotted screwdriver. If it doesn't budge, then you know the lock was the reason the lever broke and it too should be replaced. I think this mortise lock is either the 82-239 or 82-265, depending on the faceplate dimensions. Compare the images below with your old hardware to see what matches best.

Alternate image for 82-265

Alternate image for 82-239