There is an epoxy compound that would probably do the job but I can't remember the name of it. I used it once to rebuild the nose of a crankshaft on a 4x4 when the harmonic balancer came loose and chewed it away. Worked fine for the rest of the life of the vehicle. It may have been
http://www.loctiteproducts.com/p/epxy_weld_t/overview/Loctite-Epoxy-Weld-Bonding-Compound.htm. 3M also has one
http://www.3mdirect.co.uk/3m-scotchkote-epoxy-metal-repair-sg-527-1.htmlIf you try something like it, drill a few small shallow holes into the metal to give it a locating point. You could even coat a suitable bolt in grease and put it into the broken thread area such that once the epoxy goes off you could unscrew it leaving a workable thread. Everything would need to be perfectly clean around the bond site though.
