Combine sugar, butter and corn syrup in a small saucepan; cook over medium heat until thickened, stirring constantly.
Pour syrup mixture into a 13x9x2 inch baking dish.
Place 6 slices of bread on top of syrup mixture.
Top with remaining 6 slices of bread.
Combine eggs, milk, vanilla and salt, stirring until blended.
Pour egg mixture evenly over bread slices.
Cover and chill 8 hours.
Bake, uncovered, at 350 degrees for 40 to 45 minutes or until lightly browned.