Beat together the sour cream, cream cheese, vanilla and Splenda/Sugar until creamyFold in grapes (cut in half if they are over sized)Mix together for topping the finely chopped pecans and brown sugarSpread the grape salad in a 13 x 9 dish or bowl and sprinkle with topping or serve in individual cups and sprinkle mixture over.Chill overnight for up to 24 hours and serve.