Preheat oven to 350 degrees F. Grease 9x13-inch baking pan. Combine mandarin oranges and juice, eggs, and oil in mixing bowl; beat well. Stir in cake mix and beat again till well mixed. Pour into greased baking pan. Bake for 30 minutes or till cake tests done. Leave cake in pan to cool. Make topping by mixing crushed pineapple and juice, vanilla instant pudding, and whipped topping. Spread onto cooled cake in pan. Refrigerate till ready to serve.