Warm a 12-inch skillet over medium-high heat until hot. Add sausage and cook until browned, 10 minutes, stirring.
to break it up. With slotted spoon, transfer sausage to a large bowl. Spoon drippings into a cup and reserve.
In the same skillet, sauté the onions in 1 tablespoons sausage drippings over medium heat until tender and golden, 10 minutes, stirring occasionally. Add onions to bowl with sausage.
Preheat oven to 325ºF. In the same skillet, heat another 1 tablespoons drippings (discard the rest). Add celery and ¼ cup water and cook until celery is tender, 10 minutes, stirring occasionally. Stir in another 2½ cups water and bring to a boil. Pour celery mixture over sausage mixture in bowl. Stir in stuffing mix and grapes; toss to mix well.
Spoon stuffing into 9” x 13” glass baking dish; cover with foil and bake 20 minutes. Remove foil and bake 10 minutes longer, or until heated through and lightly browned on top.
Each serving: About 323 calories, 11g protein, 40g carbohydrate, 12g fat (4g saturated), 4g fiber, 28mg cholesterol, 746mg sodium.