Westbound Conrail tonnage rolls through Bridgeport, Pennsylvania on the former Reading main line. Lead unit 6440 is one of ten SD40-2’s and ten C30-7’s that were purchased new in 1977 and tracked to compare total cost of ownership for the two 3000 horsepower six-axle models. The twenty units in the study were identified by a star under the road number on the cab sides.