Awning Replacement Parts

Hello,

We are restoring some mid-century windows. They are awning windows, however, we seem to be missing the 'linkage sets' (I believe that is what it is called). The bar that is attached to the sashes in the picture. This is the only window that it is still intact. The previous owner tied string to the windows to operate them, and we would like to restore them to their original glory. Any idea as the the part we could purchase to replace the missing bar?

Thank you!