Mom's Watergate Cake

1 box white cake mix
1 box instant pistachio pudding
3 eggs
1 c. oil
1 c. sprite
1/2 c. chopped pecans
Frosting:
1 box instant pistachio pudding
16 oz. cool whip
1 c. cold milk
Topping:
1 c. sour cream
2 c. confectioners sugar
1 c. coconut

Beat all cake ingredients and spread in sprayed 9x13 pan. Bake at 350 degrees for 30-40 minutes.Combine frosting and place on top of cake. Combine topping ingredients and pour over cake.