Cream shortening with 1 1/2 cups sugar. Add eggs, one at a time, beating well after each. Sift together flour, baking soda, baking powder and salt. Stir into the creamed mixture alternately with sour cream, milk and vanilla. Pour half the batter into a greased and floured 10-inch tube pan. Combine nuts, 1/2 cup sugar and cocoa. Sprinkle half the cocoa mixture over batter in pan. Spoon remaining batter over cocoa mixture, then sprinkle with remaining cocoa mixture. With a metal spatula, cut through batter to swirl in cocoa mixture slightly. Bake in a 350º oven for 1 hour, or until cake tests done. Cool in pan about 10 minutes before turning out. Cool on rack.