The driver in a head-on collision in Frankfort last year that caused another driver to lose part of her hand will be sentenced next month.William Hinkle Jr., 35, of Frankfort pleaded guilty this week to operating under the influence and aggravated driving to endanger. He also admitted to selling marijuana and possessing cocaine. Last March, police say Hinkle was driving an SUV on Route 1A and tried to pass another vehicle.He slammed head-on into a car coming in the other direction, driven by a woman from Searsport. Part of her hand was amputated in the wreck.Police say they noticed drugs at the crash scene. They searched Hinkle’s car and arrested him.Hinckle originally pleaded not guilty last May.