Vintage Windmill and Wind Generator Forum

Hello folks.
I have a complete WC21 with a 5 spoke hub that has a cracked case. I can get a WB21 4 spoke gear box. Does anyone know if the hub and shaft are interchangeable?

WC is the model, and size code. C is 8 foot mill. WB is a 6 1/2 ft mill. all items will not switch over. The 21 you mention is the part number for the cap, or helmet.

Thank you. Saved me from making a mistake.