I had the same problem with mit '81 F-100 neck pickup. I got it rewound by a guy in Germany, who professionally creates and repairs pickups.
I sent him both pu's, because he had to have a reference and both were waxed and got 4 wires instead of 3, because I considered to have more options for a special circuit, but I didn't change the original one in the end.
I did pay the same price two Humbuckers would cost for rewinding, because he had to made him some tools, as the MFD has an uncommon format. As he surely kept the stuff, it should be cheaper for subsequent jobs.
His website is
http://www.leosounds.de/ENThe other option is to watch Ebay, every few years one appears.