Preheat oven to 350°F. Prepare loaf pan with baking spray containing flour or butter and dust with flour. In a bowl, combine flour, baking soda, spices and salt. Using a mixer, blend sugars, oil and pumpkin. Add eggs one at a time, mixing thoroughly after each addition. Slowly add flour mixture, milk and vanilla and mix until blended. Fold in chopped nuts. Pour batter into prepared pan, filling only 3/4 full. Pour raisins over the top and using a small spatula, slowly swirl raisins into the batter until evenly incorporated. Gently tap pan on counter top to remove air bubbles. Bake for 55-65 minutes or until toothpick inserted in center of loaf comes out clean. Let cake cool in pan for 10 minutes before inverting onto a cooling grid.