In bowl, combine celery salt, garlic salt, onion salt, and pepper; stir in Worcestershire. Rub on surface of beef. Place meat in a shallow roasting pan. Cover tightly with foil. Roast in a 300 degree F oven for 2-1/2 to 3 hours or until tender.
Remove meat from the pan; cool slightly. Cover; refrigerate for at least 4 hours or until thoroughly chilled. When meat is cold, cut across grain into thin slices. Arrange in 13x9x2-inch baking dish.
Combine salad dressing, barbecue sauce and sugar. Spoon over the meat. Bake, covered, in 325 degree F oven for 1 hour.
Serve on buns. Makes 16 servings.