Kevin Blackwell drafted them all in to train with his squad during pre-season and their trial period comes to a climax this weekend with two behind-closed-doors games.
The Leeds manager says he has been impressed by what he has seen, but has yet to make any firm decisions.
Lee Clark remains another possible recruit ahead of United's pre-season trip to Norway.
The out-of-contract midfielder, who left Fulham at the end of last season, is looking for a move north and has already held talks with Leeds.