Saginaw, Mich. – For the past six seasons, the Flint Firebirds and Saginaw Spirit have competed for the I-75 Divide Cup, presented by Coors Light. The Firebirds won the coveted trophy their first two seasons before surrendering it to their in-state rivals for the next three years. The I-75 Divide Cup returned to Flint a year ago, knotting the all-time series at 3-3. With a win tonight in Saginaw, the Birds have a shot at retaining the Cup another year. Puck drop is set for 7:05 p.m. (ET) at the Dow Event Center. Tonight marks the seventh of eight total…