(FORTUNE Magazine) – Mike Walsh, 49, likes Omaha, home of the Union Pacific Railroad, which he recently left as CEO. Walsh, who listens to rock music in his office, gets much of the credit for Union Pacific's turnaround. But he also helped raise $750,000 for summer camp for city kids -- in just two weeks. Another time he and Warren Buffett and Walter Scott Jr. (CEO of construction giant Peter Kiewit Sons') saved the town's Triple-A ball club by buying it up. Walsh won't have time to reminisce after October, when he becomes president of Tenneco, the $15-billion-a-year Houston conglomerate whose businesses range from submarine building to natural gas pipelines. In January he succeeds CEO James Ketelsen, 60. Walsh refuses to discuss plans for slumping Tenneco, which some say needs a sharper sense of mission. Says he: ''I've learned that you don't know what the solutions will be till you get there.'' Walsh's new job leaves one man in the lurch: Drew Lewis, 59, CEO of parent Union Pacific Corp., whose other interests include oil and gas production. The former Secretary of Transportation is said to covet a post in a second Bush Administration. Says headhunter Tom Neff, who lured Walsh to Tenneco: ''Mike was the obvious heir apparent.'' With him gone, it may be difficult for Lewis to leave. Did that make for hard feelings? Says Walsh, after a pause: ''He was supportive. I think we're okay.''