text:  In Modesto, California, a Dorito is born. Millions of chips roll out of this Frito-Lay factory every day. And while it smells pretty good in here, I'm not in town to sample the snacks, but to find out how they get from here to corner stores and grocers all over the world. This factory, one of Frito-Lay's largest, replaced its entire diesel-burning fleet with cleaner vehicles last year. From battery-powered forklifts...