Combine dates, prunes, raisins and water in medium saucepan; heat to boiling. Reduce heat and simmer, uncovered, until fruit is tender and water is absorbed, about 10 minutes. Remove from heat and add margarine, stirring until melted; cool.

Mix eggs and vanilla into fruit mixture; mix in combined flour, Equal, baking soda, cinnamon, nutmeg, and salt. Spread batter evenly in greased baking dish, 11 by 7 by 2 inches; sprinkle with walnuts.

Bake in preheated 350 degree oven until cake springs back when touched lightly, 30 to 35 minutes. Cool on wire rack; cut into squares.