Diamond, who scored a brace in a recent victory over Celtic, has earned rave reviews in his native Scotland this season. The former Scotland under-21 international would not come cheap, but is said to be set for big things.
Gunn is known to be after a defender and was frustrated in his pursuit of Cardiff City's Darren Purse by the Bluebirds' failure to find back-up. Now he is returning to his former club, where he played under Alex Ferguson more than 20 years ago, for some physical presence and leadership to add to his backline.