Preheat oven to 350°. Finely chop the rhubarb. If using frozen rhubarb, measure it while it is still frozen and thaw completely, drain in a colendar, but do not press the liquid out. In a large bowl, whisk eggs, sugar, oil and vanilla until blended and in another bowl, whisk flour, baking powder, salt and cinnamon. Add to egg mixture; stir just until moistened, peel and chop the apples and then fold them in along with finely chopped rhubarb and walnuts. Transfer to two greased 8x4-in. loaf pans and bake 50-60 minutes or until a toothpick inserted in center comes out clean.Cool in pans 10 minutes before removing to wire racks to cool. Freeze option: Securely wrap and freeze cooled loaves in plastic wrap and foil. To use, thaw at room temperature. Yield: 2 loaves (12 slices each).