I was also thinking Tommy Smith. Or maybe McGlinchey? I cant see it being Peverly or Clapham as it has been stated the reason they havnt released names on the kiwi is because hes still under another clubs contract (which effectively rules out Killen as well). Im pretty sure if it were one of these two they wouldve been released straight away and signed up asap. Theres no way their respective clubs would be delaying these two from signing for the NixAlso Vicelich has stated time and time again that hes done with professional football. I would be mighty surprised if he were to sign.
You're right, Killen's contract with Boro expired at the end of June and has not been renewed, he's a free agent at the moment.