Pella Casement Crank Replacement

I'm looking for a replacement for the crank in the attached photo. It's from an old Pella casement window. You have a similar crank unit (part number 39-392) for sale but the arm that attaches to the window is 3 1/2 inches. This crank has a 5" arm. I searched around but couldn't find anything like it. I hope you can help.