Finding replacement crank for casement window

Hi, I moved into an older house and the cranks are missing on my windows - I'd like to replace them if I can. Windows are likely from the 70's or 80's.

Here are the specs:

There's a notch in the gear, as well as a second gear at the base of the spline.
Both gears have 11 teeth.
I measured the base of the spline between the two sets of gears and it's about 5/16 of an inch. I had difficult measuring this so if that sounds off, that could be why.

Thanks for your help!