In a large bowl, stir together flour, sugar, baking soda and salt. In another bowl, combine the eggs, bananas, oil, buttermilk and vanilla; add to flour mixture, stirring just until combined. Fold in nuts. , Pour into a greased 9x5-in. loaf pan. Bake at 325degrees for 1-1/4 to 1-1/2 hours or until a toothpick comes out clean. Cool on wire rack.