Johnny Gosch was a 12-year-old for West des Moines who vanished while delivering papers in 1982. Juanita Estevez, 15, of Yuba City, Calif., disappeared on her way to school in 1984. These were the first two kids to be pictured on a milk carton. Child abduction was becoming a growing nightmare, and families and authorities were eager to try any method. Since then, postcards with photos of missing children have been widely distributed by mail,ane have proved fruitful:One in six of the kids in these and other photo efforts are recovered. As for Juanita and Johnny: She escaped from her abductors in 1986; he is still missing.