I've made bad decisions on selling guns before, I'll never do it again!! Keep it and buy another one.
I did some looking around and I am going to go with a Tactical solutions pac-lite 4.5 black matte no flutes upper $280. Its only a 100 more than threading and about the same as selling and buying a new gun. Thanks for all the great advice.
You can also buy a coupling that does not require a thread...
http://www.muzzlecouplings.com/