Thaw lobster, if frozen. Rinse lobster; pat dry. Butterfly tails by using kitchen shears or a sharp knife to cut lengthwise through centers of hard top shells and meat. Cut to, but not through, bottom shells. Press shell halves of tails apart with your fingers.

For stuffing, in a small saucepan cook green onion in the 1 tbsp margarine or butter till tender but not brown. Stir in flour and dill. Add half-and-half, light cream, or milk all at once. Cook and stir till thickened and bubbly. Cook and stir 2 minutes more. Remove from heat. Gently stir in the crabmeat and wine.

Carefully spoon crabmeat stuffing onto lobster meat. Drizzle stuffed tails with the 2 tablespoons margarine or butter.

Preheat gas grill. Adjust heat for indirect cooking. Place lobster tails, filled side down, on grill rack over medium heat. Cover and grill about 25 minutes or till lobster meat turns opaque and stuffing is heated through.