autoracks. Each Vega was fitted with four removable, cast-steel sockets inserted into the undercarriage that locked into the hooks on the bottom-hinged doors that made up the car side. The prototype car, SP 618000 was turned out in December 1968 and tested through 1969. Chevrolet conducted vibration and low-speed crash tests to make sure nose-down Vegas would not shift or be damaged in railcar collisions. Chevrolet's goal was to deliver Vegas topped with fluids and ready to drive to the dealership. To do this Vega engineers had to design a special engine oil baffle to prevent oil from entering the No. 1 cylinder, batteries had filler caps located high up on the rear edge of the case to prevent acid spilling, the carburetor float bowl had a special tube that drained gasoline into the vapor canister during shipment, and the windshield washer bottle stood at a 45-degree angle. Plastic spacers were wedged in beside the powertrain to prevent damage to engine and transmission mounts. The wedges were removed when cars were unloaded. The rail car doors were opened and closed by means of a forklift truck. The first production Vert-A-Pacs entered service in April 1970; the last ones entered service in January 1973. Besides Southern Pacific, the Baltimore & Ohio, Burlington Northern, Denver & Rio Grande Western, Florida East Coast, Illinois Central Railroad, Louisville & Nashville, Milwaukee Road, Missouri Pacific, Penn Central (Merchants Despatch Transportation), Rock Island Railroad, Seaboard Coast Line, Frisco Railroad, and Southern Railway operated Vert-A-Pacs. All were withdrawn from service at the end of the 1977 Vega model year and were reracked with conventional tri-level racks. Another joint General Motors-Southern Pacific automobile rail car was the Stac-Pac. It was designed to carry 12 high-end Oldsmobile, Buick, and Cadillac models in four removable fully enclosed tri-level containers per flat car. The first production Stac-Pac cars entered service in October 1971. Besides SP and its Cotton Belt subsidiary (SSW), Stac-Pac flat cars were contributed to the pool by the Santa Fe and Trailer Train, with the containers being supplied by ATSF, BN, D&RGW, FEC, MILW, PC (MDT), RI, Southern Railway, SP, Cotton Belt Route, Union Pacific, and by General Motors itself. All of the cars and containers were withdrawn from service at the end of the 1976 model year. Trailer Train Company Although railroads were just beginning to see the advantages that autoracks delivered in the 1960s, most North