Stir together the flour, salt and baking soda in a bowl. In another larger bowl, mix together the shortening, sugar, mashed bananas, eggs and walnuts. Add the combined dry ingredients and stir only until the batter is thoroughly blended.
Pour into the prepared pans and bake 50-60 minutes, or until a skewer or straw inserted in the center of the loaves comes out clean, or with only a few moist crumbs. Remove from the oven and let cool in the pan for 5 minutes, then turn out on a rack and let cool completely.