Preheat oven to 350 degrees. Grease and flour a 8x8-inch baking pan. Cream together butter, shortening and sugar. Mix in egg and vanilla.
In a separate bowl, mix together flour, salt, baking powder and baking soda. Alternate adding dry mixture and buttermilk to the creamed mixture. Stir in grapes.
Pour batter into prepared pan. In a separate bowl, mix together brown sugar, flour, cinnamon and pecans. Crumble in butter to form small crumbs, Sprinkle crumbs over top of batter. Bake for approximately 45 to 50 minutes until an inserted toothpick comes out clean. Cool in pan on a wire rack. Cool completely before cutting.