If unable to find the exact part I would settle for one I could make work with a cutting and caulk.


It's hard to say without the original operator handy. What's the distance between the two installation holes? Those would be the two small round holes on either side of the long oval hole. Make sure to measure them from center to center, not from the edges.
If the hole distance is 3-1/8", look at our 39-069. If it's 5", then look at 39-090 and 39-188 instead. I'm hoping you have another casement window there so you can match the arms.