The piece is 1.25"L x 0.5"W x 4.125"H. One one side there is an image of a six-pane window with a half-round on top. Below this are the numbers 2320-1061.
Bob from SWISCO responded:
November 12, 2019
Thanks for writing in. Take a look at our 82-218, or its stainless steel version, the 82-243. Carefully look the dimensions over to see if it matches your old mortise lock.