Combine prunes and water in a medium saucepan. Bring to a boil; cover and simmer 5 minutes. Drain and set aside.
Cream shortening; gradually add sugar, beating well. Add egg; beat well.
Dissolve soda in buttermilk. Combine 2 cups flour and cinnamon; add to creamed mixture alternately with buttermilk mixture, beginning and ending with flour mixture. Stir in prunes, lemon rind , and vanilla. Dredge pecans in remaining 1/2 cup flour; stir into batter.
Pour batter into a greased and waxed paper-lined 9- x 5- x 3- inch loaf pan. Bake at 350° for 1 hour and 10 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes; remove from pan.