By Daniel Bates 16 seasons and 16,000 yards later, the NFL’s third-leading rusher is ready to call it a career. On Sunday, Gore announced that he plans to sign a one-day contract with the 49ers, the team that drafted him, and retire from the National Football League. Gore will also reportedly look to join San Francisco’s front office. The football world gave Frank Gore his flowers after an incredibly productive career. “Frank Gore … will be signing a one-day contract with the 49ers and will retire from the NFL. He finishes his career with the 3rd most rushing yards in NFL history (16,000),” tw…