Former United Parcel Service Inc. CEO Michael Eskew was named Monday as the lead director on the board of 3M Co. Eskew, who retired as CEO of UPS (NYSE: UPS) in 2007, has been on 3M's board since 2003 and replaces Vance Coffman as lead director. Coffman, a former CEO of Lockheed Martin Corp. (NYSE: LMT), will remain on the board after serving as lead director for the last six years. Under the board structure of Maplewood-based 3M (NYSE: MMM), the lead director leads executive sessions of the company's…