Cook zucchini until tender. Drain well. Combine carrot, onion, soup, sour cream, salt and pepper. Fold in zucchini and combine stuffing mix with melted margarine. Grease a 1½ quart baking dish. Put a layer of stuffing mix in the bottom of dish and alternate layers of zucchini mixture with stuffing. End with stuffing layer on top. Bake at 375º for 25-30 minutes.