Cream sugar and butter.
Add eggs, one at a time, mixing well after each addition - use a mixer.
Stir baking soda into buttermilk and add to mixture.
Sift baking powder with flour and blend into creamed mixture.
Add vanilla and banana and mix.
Stir in pecans.
Pour into greased and floured 9"x5" loaf pan. (May also use 4 mini loaf pans.).
Bake at 300 degrees F for about 1 1/2 hours or until loaf tests done with a toothpick. (Bake for 50-60 minutes for mini loaves.).
Cool for 20-30 minutes before removing from pan.