Bake cake according to directions in a 9x13 pan. In a saucepan over medium heat, combine pineapple with juice, sugar, pudding, and coconut. Simmer 5 minutes. Using a wooden spoon handle, poke holes in warm cake. Slowly pour pineapple mixture over cak and spread evenly. Cool. Spread whipped topping venly over cake and sprinkle with nuts.