By Linda Chiem (July 9, 2015, 8:27 PM EDT) -- Lockheed Martin Corp. and Textron Inc., two aerospace and defense contracting giants, are the final contenders to buy United Technologies Corp.'s helicopter unit, Sikorsky Aircraft Corp., which could be valued at around $8 billion, Reuters reported Thursday. United Technologies said last month that it would sell or spin off Sikorsky to focus on core businesses, and is now weighing offers from the two companies and may pick a buyer by month's end, according to the report. But it's not a sure thing just yet, because United Technologies could still change its mind on a sale and instead spin off Sikorsky to shareholders in a tax-free deal, the report said. With a $60 billion valuation, Lockheed is the larger of the two suitors. Textron, whose market capitalization is closer to $12 billion, has reached out to private equity firms to put together a cash bid for Sikorsky, Reuters said....