In a shallow baking dish, mix the salad dressing, garlic powder, and salt. Place the chicken in the bowl, and turn to coat. Marinate in the refrigerator at least 4 hours. (For best results, marinate overnight.)
Preheat the grill for high heat.
Lightly oil grate. Discard marinade, and grill chicken 8 minutes on each side, or until juices run clear.
Per Serving: 455 calories; 34.2 g fat; 12 g carbohydrates; 25.1 g protein; 67 mg cholesterol; 2469 mg sodium.