I'm replacing and old Rittenhouse doorbell transformer as part of a smart doorbell upgrade. My problem is that the screw spacing of the cover (of which the transformer is embedded) doesn't seem to match any modern-day cover spacing.
The transformer is part of a 4" door cover; there's several joined circuits inside the box so I really don't want to have to replace the box itself. But I can't find a cover that meets these screw holes - they are 7/8" from the opposite sides and 3/8" from the top/bottom (in the pic they are the upper right slot and the bottom left hole). A standard 4" box cover does not line up with these holes at all.
The diagonal hole-to-hole measurement is 4 1/4". Also note, my goal here is a plate with a 1/2" knockout to mount the new transformer. I've got an existing 4" plate (that I could drill out, I presume) if that's the best way.
Any thoughts on what might work here? Is this spacing called something else that I'm not searching for correctly?