Combine the sugars, corn syrup, salt, milk and margarine in a large heavy saucepan. Cook over medium heat stirring constantly until sugar is dissolved. Stir frequently until mixture reaches 236º on candy thermometer or until it forms a soft ball when dropped in cold water. Remove from heat and cool for 2 - 3 minutes. Add vanilla and nuts and beat with wooden spoon until mixture begins to thicken. Quickly drop by spoonfuls onto greased foil. Allow to cool.