Operating Era: 1922-1975. Now Includes our one-piece roof frame. Union Refrigerato Transit Line, Chicago, Milwaukee, St. Paul & Pacific, Erie, Minneapolis & St. Louis, Bordens, College Inn, Gerber, Pabst, Miller Beer, North Western Refrigerator Line. AC&F revised its standard reefer design in 1922, using a higher door with modern appliances and ladders rather than grab irons. Thousands of cars were sold to Union Refrigerator Transit Co., North Western Refrigerator Line and other companies which painted hundreds of different billboards on them.