I'm having a bit of trouble with this one, myself. They don't really make parts for windows like this anymore so it can be difficult to find even rudimentary parts like this. That said, it is just a flat, "L" shaped piece of metal. I have to think that you can probably hack something into working in the same capacity.
One thing that comes to mind is our butterfly clips, 70-041 and 70-042. These appear to work under the same principle but come pre-riveted to a base. I think if the size is right you could potentially get these to work if you drill that rivet out and install the "L" piece onto the window with a screw. The legs of that piece are approximately 1-3/8" long on each side. Just note that any product altered in that way cannot be returned for a refund.
For now, look these parts over and see what you think.
Anytime! Best of luck, and please feel free to reach out if you had any questions.
