Preheat oven to 350 degrees.
Mix 1 c. flour with salt, baking soda and Splenda. Cream margarine,adding flour mixture.
Add beaten eggs to flour mixture and mix well. Add remaining flour and buttermilk alternately.
Add vanilla, bananas, nuts and mix well.
Pour the dough mixture in a standard size loaf pan greased and floured lightly.
Bake at 350 degrees for 1 hour and 15 minutes.
Cook bread on its side.
When cool, wrap in foil or store in plastic in refrigerator.