There are a few making these as replacements. One guy was making new ones in his machine shop, and claimed to have modified the extractor profile so that breakage was minimized. I forget who that was, but he had a website, and I found it by a Google search.
Midway has the Callahan extractor for pre-64's.
http://www.midwayusa.com/product/515...l-in-the-white
Check here:
http://www.williamsfirearms.com/Index.htm