Preheat oven to 325 degrees. Grease and flour a 9x13 pan. In large bowl, beat eggs. Add boxed cake mix, add oil and mandarine oranges to the batter (add juice as well as the fruit).
Pour batter into pan. Bake for 40 minutes at 325 degrees. Cool on a wire rack.
Frosting: While cake is baking, prepare frosting by mixing together whipped topping, the package of instant pudding, and the crushed pineapple with its juices. Set frosting in refrigerator to set. Frost cake when it is cooled completely.