replacement crank handles needed

I have some older louvered style windows in a shed that I need to find replacement crank handles for and possibly the geared operator that the handles attach to for some of the windows. I measured the splined shaft that the handle attaches to and it looks to be very close to 5/16 diameter. It also has 12 splines. Can you tell me if there is a replacement handle available that is metal not plastic? It can be slightly shorter than the original handle (maybe 1/2" shorter at the most) Thank you for your help