Random Recipe Monday - Grapefruit cake

Ok, this one really is random. It is from my 1940s cake recipe book and I've never tried it or even thought about using grapefruit in a cake. But, I must adhere to the laws of fate that give me a random recipe, so here 'tis:

3 3/4 cups sifted cake flour
1/2 tsp salt
1/2 tsp baking soda
3 tsp baking powder
1 c shortening
3 tbsps grated grapefruit rind
2 1/2 c sugar
4 eggs
1 egg yolk
3/4 c grapefruit juice

Sift flour, salt, soda and baking powder together. Cream shortening with grapefruit rind and sugar until fluffy. Add whole eggs and yolk, one at a time, beating thoroughly after each is added. Add sifted dry ingredients and juice alternately in small amounts, beating well after each addition. Pour into greased pans and bake in moderate oven (350 degrees) 30 to 35 minutes. Make 3 (9 inch) layers.