Preheat oven to 350 degrees. Grease and flour a 9x5x3-inch loaf pan.
In a large mixing bowl, using an electric hand mixer, beat together the sugar and vegetable oil. Add Peach Schnapps or peach nectar and vanilla. Add eggs, one at a time, blending well after each addition.
In a separate bowl, whisk together flour, baking powder, baking soda, salt and cinnamon. Slowly add the dry ingredients to the wet ingredients. Beat until well combined. Stir in diced peaches. Spread the batter into prepared loaf pan.
STREUSEL TOPPING: In a small bowl, using a pastry blender or fork, combine all ingredients. Sprinkle over the top of batter. Bake for about 55 to 65 minutes, until a toothpick inserted in center comes out clean. NOTE: After 30 minutes of baking, cover the bread with foil to prevent the top from burning.
Cool on a rack in pan for 10 minutes; remove from pan to cool completely.