Preheat oven to 325°. Grease and flour 2 (9 x 5 x 2 3/4-inch) loaf pans. Stir together 1/2 cup of the sugar and the cranberries; set aside. Stir together flour, rest of sugar, baking soda, baking powder, salt and spice and set aside. Beat together pumpkin, oil, buttermilk and vanilla until combined. Beat in eggs. Stir in flour mixture, then cranberries and sugar. Spoon into prepared pans and bake 1 hour, or until wooden toothpick inserted in center comes out clean. Turn on wire rack to cool.