1 1/2 c. sugar
9 c. water
1 (12 oz.) can frozen grapefruit concentrate, thawed
1 (12 oz.) can frozen orange juice concentrate, thawed
2 c. apricot nectar
3 1/3 c. lemon-lime carbonated beverage, chilled

Combine sugar and water in a large Dutch oven. Bring to a boil, stirring until dissolved. Remove from heat and cool. Add grapefruit and orange juice concentrates and nectar, stirring until blended. Freeze 8 hours. Remove from freezer 20 minutes before serving. Stir in carbonated beverage. Serve.