Preheat oven to 325 degrees F (165 degrees C). Grease and flour one 9 x 13 inch baking pan.
Cream the 1 cup butter or margarine, shortening and 3 cups white sugar together until light and fluffy. Beat in the eggs one a time beating well after each addition.
Beat in the flour, lemon extract and lemon-lime soda. Mix well and pour batter into the prepared pan.
Bake at 325 degrees F (165 degrees C) for 1 hour.
To Make Icing: In a saucepan combine the 1 1/2 cups white sugar, 1/2 cup butter or margarine, 3 eggs, coconut, pineapple and nuts. Cook over medium heat, stirring constantly until mixture is thick. Pour over cake while cake is still hot and icing is bubbling.