A five-year-old Galt boy has been killed in a collision between the van he was in and a car on Highway 12 in Lodi. The highway patrol says the boy was not properly restrained in the van when it was hit by the car yesterday. Guadalupe Sanchez of Stockton was booked for investigation of drunken driving. Sanchez was listed in critical condition at San Joaquin General Hospital with major internal injuries. Investigators say Sanchez was eastbound when his car crossed into the westbound lane. Two adults in the van were not hurt.