That, and the mechanical link between winder and camera is very different from that on the 500 C/M.
If you want to use a winder CW, you need the 503 CXi (only the version with that "i") or 503 CW.
There was an aftermarket winder available in the 70's, IIRC, for the 500CM series bodies. Check around on Fleece-Bay, keh.com, or your local camera swapmeet.
Eric