I need upper and lower "arms" and right and left side cranks as well. I'm very frustrated about getting these parts so I can open and shut windows. Call me to troubleshoot if pictures aren't enough.
I'm sorry to say that I don't recognize this operator off hand. The design is a little peculiar, and almost looks like a mish-mash of different components from other assemblies. Either this is an older style or something the installers made to work in this application. That would explain why you haven't been able to find anything.
Either way, based on what I can see I would say that our best option is going to be the 39-220B. This has the same style link arm with the downward facing offset, while still being mounted above the gear arm. My biggest concern is that the width of the base is going to be much larger than yours at 4-15/16". Make sure to check that before you buy anything.
If that width ends up not being the same, please remove your operator from the window so that we can get a better look at it. I might be able to find something closer, but I have to see the entire assembly without obstruction to get a better look at the smaller details.
