Beat eggs with electric mixer. Add cake mix, oil and mandarin oranges (with juice). Mix for 5 - 10 minutes. Place in 3 8" or 9" greased and floured cake pans. Bake 20-25 minutes at 350 degrees F. For frosting, place Cool Whip, instant vanilla pudding and drained crushed pineapple into mixing bowl. Add 1/2 juice. Stir to combine. Place in refrigerator for 1/2 hour to thicken. Add remainder of juice to mixture. Frost cake when cool and refrigerate.