Welch’s Grape Juice with a plain “K” is not an Orthodox supervision and should not be considered Kosher. Only specially produced bottles of Welch’s-Manischewitz Kosher Grape Juice with an O/U on the label are acceptable.
From The COR of Greater Detroit: Newly Certified Sodas
The following new Sodas are Kosher/pareve with no symbol required… Mountain Dew Baja Point Break Punch Mountain Dew Baja Laguna Lemonade Canada Dry “Fruit Splash”