The investment banks have sent term sheets to a host or prospective buyers, added one of the sources who spoke on condition of anonymity because they were not authorized to speak to the media.
Representatives for Lendlease and Morgan Stanley declined to comment. Gresham did not return requests for comment.
The Australian developer wants to divest the E&S unit, which Bank of America Merrill Lynch analysts have said could fetch about A$500 million ($355.15 million) in cash proceeds, and focus on its other three units - construction, development and property investments.
In a presentation on Thursday, Lendlease said it expected to take a restructuring hit from the sale of between A$450 million to A$550 million.
LendLease last month reported a 96.3 percent drop in first-half profit, dragged down by the underperformance of the E&S businesses, which was hit by delays and low productivity in a tunneling project in Sydney.