The club have announced that they are in talks with Burton and MacLean's representatives as well as offering Bullen a new contract.
Burton and MacLean are both scoring goals for fun at the moment with the former Derby striker and the Scot scoring 24 goals between them this season.
Jamaican international Burton is going through a purple patch and has notched four goals in his last five games.
MacLean earlier was growing frustrated with life at Hillsborough and that showed after the victory over Southend but now is playing with a smile on his face again - and said last week to Footymad he wants to stay at S6.
Bullen's inspired performances this season have seen the club offer him a new deal and Brian Laws has expressed his pleasure in his displays recently.