In a bowl, combine celery salt, garlic salt and onion salt, pepper and Worcestershire sauce. Rub on surface of beef.
Place meat in a shallow roasting pan. Cover tightly with foil
Roast in a 300° oven for 2.5 to 3 hours or until tender.
Remove meat from pan, cool slightly. Cover and refrigerate.
When meat is cold, cut across the grain into thin slices.
Arrange in 13x9 pan. Combine salad dressing, bbq sauce and sugar.
Spoon over meat. Bake, covered, in a 325° oven for 1 hour.
Serve on buns.