Cream margerine, shortening, and sugar. Add egg yolks. Beat. Add soda to the buttermilk, then add alternately with the flour to first mixture. Add salt, vanilla, coconut, and pecans. Beat until fluffy, then fold in the stiffly beaten egg whites. Bake in the tube pan (or spring form pan) in 350° oven till done -- about 30 minutes. Ice with the cream cheese frosting.
Nadine Coleman of Memphis bakes this. It is a lot of trouble, but very good.