The classic and antique automobiles at Hagley’s annual Car Show are meant to impress. And the 604 handsomely restored vehicles at yesterday’s show did not disappoint. Some 15,000 auto enthusiasts browsed and peeked at cars and cabs parked one after the other on the lush lawns at Hagley. But one “featured” vehicle — a Ford pick-up truck built for drag racing — was a bit more unusual than others because it is the only one in existence, and apparently the only one ever built. Owner Bill Naudain of Claymont is somewhat of a legend among antique pick-up truck enthusiasts. He “paid” 13 cows for this one-of-a-kind truck back in 1963, which he says is now worth over $2 million.