It is easy to find these generator heads that are used and very cheap when the engine dies. They are an induction generator where the spinning armature is made from electro-magnets (coils of copper wire) instead of permanent magnets.
They are wound to produce 110 VAC at around 3,000 RPM's, and they are the least appropriate donor to try and modify to produce 12/24/48v from wind. I have not converted one, but others have, and I trust when they say its too much work to result in too small an output.
Research this site for "Zubbly motor conversion" and also "GE ECM motor".
Permanent Magnet Motors (PMM's) are easily converted to a wind powered Permanent Magnet Alternator (PMA), it might be good to research those too. Best of luck.